So you have created your character and are given 2 options after you are done with him/her:

1-Play through the tutorial:
You will start the game at Day 1, and be walked through knowing the basics of playing the game.
You might want to select this option if:
This is your first playthrough of the game.
You wish to learn the basics of the game in an non-punishing environment.

2-Skip the tutorial:
You will be placed at Day 4, with full control over the preferences menu and at the 1st day of your restaurant opening for business.
You might want to select this option if:
You are familiar with the game controls.
You wish to select and test the preferences of the game to suit your own style of gameplay (make it easier or more challenging right at the start). Note that choosing to play the tutorial will lock the preferences menu until Day 4, therefore skipping the tutorial is advisable if you want to explore the preferences as soon as possible. This can be changed at any time during gameplay (as long as your menu is not locked for the day, meaning your fridges are empty).
You wish to learn on the go (meaning learn through self discovery over a tutorial forcing you to do things at certain times).

At the start of your journey, you will have a single kitchen staff element to help you out, that can perform limited tasks for you (cleaning up the restaurant only at the start). It is advisable to invest as soon as possible in the following upgrades:
3 Refrigerators (the max number of them, used to store anything the game considers "fresh" for use in the service. You do this by preparing the items beforehand after you stock the fridges). Each Refrigerator can stock up to 9 items at once.
3 Warmers (used to store some items the game considers "hot" in their original containers that are prepared pre-service to use during the service, working in a similar way to the refrigerators). Each Warmer can stock up to 2 items at once.
3 Heat Lamps (because they can only be used during the service and anything left in them before the service will get deleted afterwards, when the service starts, this makes it the least of your priorities during the Early Game to get. Nevertheless, they still get placed over other items required for the more advanced recipes).
Other items (depending on the recipes you want/have available/need to learn for quests). Note that priority should be given to several cooking ranges (most widely used items for preparing recipes), followed by wooden chopping boards (large ingredients prep station), cutting boards (small ingredients prep stations and last, but not least mixing tables). The remaining items are dependant on the recipe path you wish to go for and are, in order, sink, blenders, spice rack, cookware station, blender, dough station, meat grinder, meat slicer, oven, wood-fire oven, bamboo hangiri (the latter 2 require their respective DLCs to be available).

It is important to note that by this time you will also be introduced to the concept of Responsibility and Hygiene:
Responsability: This affects your kitchen staff morale, certain actions will lower or raise this bar, depending on their consequences. It refers to how eco-friendly your restaurant is when dealing with waste and how well it contributes to your local economy.
Actions that lower the bar:
-Using the trash bin to get rid of food.
-Throwing away storage goods.
-Buying items from cheap international suppliers.
-Choosing certain options that lower responsibility during random events.
Actions that raise the bar:
-Buying items from local suppliers,
-Choosing certain options that raise responsability during random events.
Actions that have no impact on the bar:
-Buying items from national suppliers.
-Packaging food.
Hygiene: Pretty self-explanatory. This affects how clean your restaurant is. A cleaner restaurant will result in less odds of having to deal with a event called "sanitary emergency" (which usually involves pests in the storeroom that must be dealt with as soon as possible). This might happen too if you have a lot of supplies (from random events, that you get for free) or if you over order supplies because you have the cash for it (more on this in the advanced section of the guide).

Note that this is by far the hardest part of the game so it is recommended to have a 3 dish only menu as the more items you need to order the more funds you will need to spend them and at this stage you are not exactly rich and you need that income you get from the services to invest in workstations that will inprove your efficiency of service (like refrigerators and warmers).

I consider the mid game of your journey the stage where you meet the influential characters and start getting your kitchen staff story quests and meet the remaining members that will soon join your kitchen staff.
It is important to complete your kitchen staff requests to avoid them being locked down in a certain level for long (as they will be more useful the higher their level is). This is also a good time to introduce you to their specialities, as well as giving you the full kitchen team names:

-Kitchen staff specialities: This just means they will cook a dish related to their speciality faster than a teammate without that speciality. The dish grade will still be dependant on the character level, as well as what he/she was ordered to do. They are as follows:
Kassim: Seafood/Fish
Adele: Meat
Jiro: Vegan/Vegetarian
Note:Some dishes are bugged and will not trigger the kitchen staff speciality buff (which means any member of your team will cook them at the same speed, regardless if the dish is a dish they specialize on or not). Therefore it is recommended to find a menu at this stage that tries to incorporate dishes that are related to your current kitchen staff specialities (requires experimentation as to find the dishes that are not bugged).

Once their level is high enough and at this stage you should have the ability to assign your team to the following tasks during pre-service hours. However, be very mindfull as they might not want to clean up that day and that will show up in the tasks wheel as a warning if hovering the clean up the restaurant task.
-Clean up the restaurant: This will raise your hygiene bar (it decays naturally every morning so at least 1 team member should be assigned to clean the restaurant every day, preferebly the one that is ok with doing so). Up to 2 team members can be assigned to this task. However only 1 is enough to raise the hygiene bar to the max.
-Prepare extras: This will make it so your teammate will prepare extra plates that generate income for you at the end of that days service (apears on the after service report as "extras"). Up to 1 teammate can be assigned to prepare extras.
-Help prep food: Up to 2 teammates can be assigned to help you prep food. This will move them to the prep station. Unlike the service you have to select the edge of the prep station to order them around (the edge will say prep station and a prompt to select it and is located the nearest side to the plating station (its a smaller area than the prep station where you collect the food your team has prepped).
-Clean the storeroom: 1 teamamate must be assign to this task. Only appears during the "sanitary emergency" random event. You will get a notification pop up once he/she has dealt with the pests and the storeroom is clean.

This is the stage where you unlocked your full kitchen staff already and met all the game characters. You will be working towards the awards, growing up your kitchen and dining room and overall getting your restaurant bigger, better and getting those awards that will move you to the end game. By this stage you should have your full kitchen staff team as well as be making progress through their Story quests.
To expand your restaurant you should be a certain level (depending on the level of the expansion you wish to do). For example, the max level expansions will require a minimum character lvl of 26. It is worth noting that you should expand at a steady rate meaning you should have enough equipment to fill up all the new empty space you will get with a kitchen expansion, for example (in order to maximize efficiency). Much like the kitchen expansion, the dining room expansion will make services last longer thus require you to have more kitchen space too as to place all your stuff you need to cook more efficiently.
To expand your facilities all you need to do is interact with the blueprint icon on either the dining room or kitchen and choose an upgraded layout. Note that you will need to sort out your decorations again as they will reset once an upgraded expansion is applied.
This is also the perfect section to talk about optimizing your kitchen. About why is this important and why this is different for everyone.
Kitchen optimization: The basics of a layout devided by workstations.
What does this model entail?
This is a very common model (I am by no means a real life employee of the restaurant industry but I did my research on the topic). The model entails different spaces dedicated to certain equipment in order to maximize efficiency from point A (said stations to prep food) to point B (said stations to cook food) to point C (said stations to store food) to point D (the plating station). Common concepts are the triangle shaped areas or a square like circuit, In my current restaurant I use the square like circuit where the cooking area core stays at the middle (grill, fryer, cooking range) and are supported by nearby prep equipment (spice rack, sink, blender, dough station, meat grinder, meat slicer, oven, wood-fire oven, bamboo hangiri). The store stations are on both sides of the square (warmers and heat lamps closer to the plating station and refrigerators close to the sink and packaging station). Note that this is the model that works for me, my gameplay, my restaurant and was improved upon through hours of experimentation. Note than you need some free space worktops too to dump anything from dirty trays/baking dishes or trays/baking dishes that have baked goods from the oven to retrieve them to ingredients temporarily. Yours might be completely different and unique.
Its also important to note that there is the ability to change your character name, gender, restaurant name and outfits/appearence at any time during the dashboard panel/your character locker to reflect your in game achievements or simply equip unlocked stuff through gaining gameplay badges. Its also worth noting that by this stage the use of free roam mode (staying after the service is over mode) will see more frequent use as you aim to upgrade and learn more recipes at this stage of the game and by now you should be running a full menu and be on your way to the awards (described in the End Game section).

So you completed all of the other parts of the guide (including maxing out your kitchen staff levels). Fear not, as the game is not over and provides a lot of replay value at end game. There is a lot more to achieve and some of it is not locked once you achieve it. I will not go over achievements as for that there is already a Steam guide on the matter. However, there is a lot of side content to explore at end game. So here is the list:
-Side character stories: This will unlock unique cosmetic items, depending on the character story you complete (like unique clothes and decorations once you complete those side character story quests).
The last story quest: This is unlocked once all character story quests are completed and triggers the special service called "Celebration Service quest" (which is shall I dare say the epic finale quest).
-Fully upgrade all your recipes: Once you reach max level you can learn all the recipes in the game (depending on which DLC you own).
-The Cooking Lab DLC: This is a free DLC. It allows you to create custom recipes and add them to your restaurants menu. I have not tried it yet in a comprehensive way.
-The awards: They can be won multiple times. The first time you win one it will unlock the respective badge, as well as a unique cosmetic item related to the award. However, you are not locked once you earn an award. You can choose to go the other track and earn the other badge and switch back and forth as many times as you want. The only exception is the Guide Selection award that once won will permanently stay on your restaurant (this is necessary for the other 2, and arguabely more important awards: The Bib Gourmand Gastronomic Unpretentious menu award and the Michelin Guide Star Gastronomic Gormet award). All you have to do is have at least 3 Gastronomic level dishes in your menu and switch back and forth as to reset the awards progress. It takes about 10-15 services with an overall rating between 85-100 to get an award using the same track.
-Earning Gold Coupons: Used to unlock cosmetics that require this currency in addition to money.
-Daily Challenges: Unlocked early in the game, they gain more relevance as you clear more and more of the game content. Those rewards money and Gold Coupons, in addition to experience (that becomes irrelevant once you reach max level.
-Earning Blue Coupons: From a specific character once you complete his side story he might drop by your restaurant asking for a favour and in return you will get these discount coupons for the Catalog store.
-Earning Green Coupons: From a specific character once you complete her side story she might drop by your restaurant asking for a favour and in return you will get these discount coupons for the Catalog store.
-Side quests: Usually delievered by a specific character they ask you to do certain stuff for rewards like money, costumer boost, responsibility boost rewards, etc...

Specific section with content unable to fit anywhere else:
-The catalog: This is where you buy all your stuff (from kitchen to dining room equipment and character outfits). Its located in your office, right next to your Dashboard computer.
-The dashboard panel computer: This is where you check your resturant information, team status, your restaurant name, service history and influential characters known to you in the city through the story of the game.
-Your character locker: Where you change your character appearence.
-Your office armchair (clock): Allows you to advance time forward (you can stop this at any time or it will automatically stop once an important event is about to happen (random event, side quest, service available event, etc...note that you have to stop the clock manually to collect deliveries you ordered and the clock will not automatically stop if your team is prepping food and is done with it. The clock will also not stop once your team is done with the extras, maximum 6 extras/day. The clock will also not stop once your restaurant hygiene is maxed out through your teammate cleaning actions. The clock will also not stop once your team arrives in the aftrenoon and so that must be stopped manually as well).
-The blueprints panels: Where upgrades to your restaurant are done.
-The storeroom: Where your products are stored. Also you can manage your stock here via the stock management pad as well as order stock for the daily service/side quests.
-Packaging station: The station where you dispose of things ecologically. Takes more time but you do not loose responsability for using it.
-The Trash bin: The object that allows you to get rid of stuff much faster. However, this will lower your responsibility bar by a lot. A single item thrown here by accident will hurt your responsibility like a truck. The same is true if you throw away items in your storeroom. Freezing them does nothing to your responsibility bar on the other hand. It is not advisable to get rid of items this way unless you have lots of money to buy locally to raise your responsability bar faster that way or your goods have expired and cant be frozen in the storeroom for that reason.
-Codex: Contains all the tutorial information unlocked up to that time for future review. Acessed from the Pause menu.
-Preferences: Contains all the game preferences information. These can be changed at any time as long as you haven’t stocked your kitchen for the day. Acessed from the Pause menu.unlocks on Day 4 once you finish the tutorial (or directly on Day 4 if you choose to skip it).
Trivia:
-After the last story quest named "Celebration Service quest" is over the game is oficially complete and enters the game Finale stage and you are placed back in your restaurant now super dirty from the festivities and you are free to play the game on that save file without the pressure of having to complete the storyline of the game. This effectively means the game has infinite replay value. You can keep playing on a save game that reached the game Finale or you can create a new save and restart a new restaurant if you so desire.

I hope you find this guide useful on your journey to become the next Michelin Guide Star Chef.
Please feel free to let me know if I miss some advices or things you might have noticed in game that I have not yet.
Thank you for your time and reading my guide and for your passion for this game. Stay safe everyone and happy cooking :)