There are plenty of guides that go over the basics to this game so I will try to keep this short. TL;DR at end.

Practice in training and firing range

• Use these tools to learn movement, weapons, and abilities of your legends.
  
• Adjust keybinds, adjust your mouse sensitivity and DPI, and change your performance settings.
  
• It's best to have at least a stable 60-100+ FPS.
  
• Use the practice dummies to learn how to aim as well as bullet spread/ range.

Guns I find easy to use

• Flatline
  
• R-301
  
• Eva

If you're accurate with your shots or like sniping, there are all kinds of guns for that. Try the Wingman, Triple Take, Sentinel, Charge Rifle, etc. Peacekeeper is the best shotgun for good shots, but learn the choke. A lot of it comes down to personal preference and learning by experience.

How to get better

• Jump in games and just play. You can queue up solo in duos or trios if you want. But just play, learn the movement, learn sliding, learn weapon range, loot spots, etc.
  
• Watch streamers or YouTuber's who are good at the game with a grain of salt. It's okay to take advice from others and learn good habits, but the quickest way to get killed and frustrated is by trying to copy strats of people who have been playing for 1000s of hours and failing due to inexperience.
  
• You are going to lose a lot. You are going to die a lot without getting a kill. Pay attention to what you may have done wrong and play differently next time.
  
• Ultimately, find what works for you and get better at it. There are general things you can do to help everyone, but Apex is a very situational game and all Battle Royales have a degree of luck.

General Advice/TLDR

• Learn how to move. Crouching/sliding is important so bind it to a good key.
  
• Learn how to ping. Pinging is extremely important, especially to those hard of hearing, and I consider it more important than voice chat.
  
• Use grenades, they are good in this game.
  
• Remember your abilities and heals/shields.
  
• If playing with a team, try to communicate and use voice if possible.
  
• Loot somewhat separately but stick together when possible.

Legends I like and my reasons why. All good for solo but work well on teams.

Mirage

• Easy to use/understand abilities.
  
• Can hide and use decoys to distract, also helping the team.
  
• Can escape from almost any gunfight using ultimate.
  
• Makes you and teammate invisible when reviving them.
  
• One of the most fun personalities in the game.

Caustic

• His dialog is funny.
  
• Gas traps can block doors or choke points.
  
• Perfect for solo, you can camp in buildings and take smoke breaks.
  
• Gas grenade is okay in power but also blinds people or can be a distraction.

Valkyrie

• Fun jetpack movement, easy to escape.
  
• Ultimate flies you and your team out of an area.
  
• Rocket tactical is fun and easy to use.

Lifeline

• Abilities are very helpful but require next to no thinking.
  
• Drone heals you or teammates.
  
• Can revive people without being glued to them.
  
• Ultimate usually gives good supplies.

Bangalore

• Smoke tactical lets you escape gunfights.
  
• Ultimate is fun and deals heavy damage.
  
• Move faster when enemies see you.
  
• Pings give extra info on items, useful for noobs.

Rampart

• Sheila is powerful and wins gun fights with no loot.
  
• Tactical barriers are great for camping and taking smoke breaks, as with caustic.
  
• LMGs are better when playing as her.

Bloodhound

• Tactical lets you see enemies through walls at a range (but they can see you using it!)
  
• Ultimate lets you escape from almost any situation and see everyone.
  
• Passive tracking is a huge awareness boost.
  
• Great for teams or solo play.

Wraith

• Can escape quickly from situations with tactical.
  
• Can teleport with ultimate.
  
• Is the streamer meta so people will naturally fear you in gunfights.

Seer

• Great enemy awareness, which allows for helpful teamplay or solo camping/smoke breaks.
  
• Ultimate is basically a wallhack.
  
• Like bloodhound but better for teamplay IMO.

There are others that are good, but I personally don't have much experience with them yet, so forgive me if I didn't include your favorite.

How to be a chill teammate

• Never get angry at your teammates when you die, even if you think it was their fault.
  
• If you're angry anyway, refrain from making it known to your team.
  
• It's okay to provide helpful advice, but also remember to think from the perspective of your team and listen to them.
  
• If you blame your team for every loss you have, re-evaluate yourself or play solo, because there is guaranteed to be mistakes you're making as well.
  
• Ping, ping, ping. Say thanks. Use the mic but don't be toxic. Let your team know where you're going or stick with them.

Most important, continuing from above:
This is a battle royale. It involves a heavy degree of luck. No matter how great you are at x or y, you are still going to lose, people are going to make mistakes, and sometimes you're just going to have bad luck. Of course there's a high degree of skill involved as well, and the top players can perform well consistently, but that's probably not going to happen for the type of person reading this guide. In order to be the best, it becomes much more of a job than a game. If that's what you enjoy, then at least learn to respect the playstyles of your friends if you plan on playing together, or communicate your intentions with them.

Guide to randoms

• If you queue up with randoms and they are toxic, mute squad. If they still find ways to be toxic, leave, suicide, or troll. If they are not toxic, treat them like any other teammate and help them out. You might find a friend.

Red flags for bad friends\teammates

• People who pay way too much attention to streamers\reddit\the meta.
  
• Passive aggressiveness, lack of communication, alienation.
  
• Blaming teammates for every mistake.
  
• Eagerness to teach but unwillingness to listen.

Last but not least, take this with a grain of salt.
This guide is intended for chill players who still want to enjoy the game, or for competitive players who want to better understand how to enjoy the game with their more-casual friends. The advice above may not get you kills or wins as often, but they will still come, and you will keep your sanity in the process.

https://youtu.be/zVWVPaXaouo?t=26

Go with the flow

• Ultimately, having the right mindset and energy while playing will help you more than anything.
  
• Going in with a good attitude and mood will naturally cause you to perform better.
  
• Conversely, being overly negative or generally being a toxic person will naturally cause you and your team to perform worse.

See a car? Take it. It might get you killed, but at least it'll be funny. Accidentally popped an ult for no reason? Oh well. Spam voice emotes, drop banners, inspect your gun. Play like you don't care too much and luck will be on your side. You may not end up being the best, but you will still have fun most of the time.