The best way to level your EGO rating is of course by doing missions.
Main missions will not only give you knowledge of the story of Defiance, but it will also give you a lot of Items, Money and of Experience.
Main missions will give you the most experience and you do these first.

There are also Side missions, these are smaller missions, which can also be found on your map. These normally give around 2000 experience and a weapon mod. Side missions are small and easy to finish, though, some might be bigger.

My experience with doing these missions is that I leveled around 1500 levels already, without doing anything else!

You can check if you have done ALL Main- and Side missions by looking in the Legend on the map. If there is an Icon for one of these two, then you didn't do all the quests, keep going!

After you have done all the work with the Main missions and the Side missions, the leveling won't slow down a bit!
There are a lot of things to do without missions. For example you can do: Incursions, Sieges, Arena's, PvP, etc.
The best thing to though, is to start farming Achievements, these are called Pursuits. You can check them by pressing the J-button.
Most of the Pursuits are easily done by yourself and will give you a lot of EGO rating once completed. There are a lot that give you 5 rating, but also with 10, 15 and even more!

I started off with the mini-games, such as: Time Trial, Rampage and Hot Shot. By doing them and finishing them with at least a silver medal, will give you credit on your Achievements.
With doing all these and finishing all of them with at least a silver medal, will already give you around 200 EGO rating.
Not only doing those mini-games will help you. To complete the whole achievement and to get your rewards, you will also need to discover certain places and you need to find Data Recorders.

By doing these 3 things, you can get a lot of rating, I would guess around 400-500 extra EGO rating, just by doing small things. And that is only in the Season 1 Achievement section!

An easy way to do these achievements is just by looking up the things you need to find on the internet. A really handy website for that is: http://www.defiancedata.com

Of course you need to relax sometimes. It can become boring, farming Pursuits all the time. We have to relax once in a while.
In that case you can do some dailies and events.

Dailies can also be found by pressing the J-button, in the second tab.
The only dailies you can not do on low level are the expert-maps and the Chimera dailies.
The rest can be done within 24 hours, then you can do them again. Weeklies can be done only once per week.

All these are pretty easy to do. Finishing them will give you experience, a certain amount of money and Faction Currency, which can be used to buy items from a specific vendor.

The events can be found anywhere in the game. There are the small events, which can't be found on the map and are randomly spawned on places. Then there are Incursions, Sieges and Arkfalls, which give you a lot of experience and will help you level your weapons too. You will also get a lot of items, some are even useful!

These events are a lot of fun, in the bigger events, such as the Volge Incursion at Kenn's Farm and the Major Arkfalls are really popular amongst the players. Go there and you will find 30 or more players fighting the same enemy.
The more points you get, the better the prize will be.

You can also summon your own Arkfalls, but you need a DLC for that and you need to do a small quest-line for it.

Weapons are leveling as you play. Just by using weapons a lot, they will level up. Weapons and vehicles too, will level to a max of level 20. They will also give you around 200 EGO rating for leveling all of them to level 20.
You can specifically train them or you can just do other stuff and wait for the guns to level up while you play.

It's really easy to level, but it takes long. Vehicles goes pretty fast though, just use your vehicle as much as you can. Even when it's just a 100 meters you need to walk, just use your vehicle ;)

A good way to level your weapons is by doing a certain side mission. Follow the instructions in the clip below and make use of it: https://www.youtube.com/watch?v=ifDeQ0M8E1o

If you are not able to do this side mission, then you will have to just shoot every enemy you find :D

So this is the thing you have been waiting for all the time while reading this guide.
There are many ways to level, but eventually it won't go fast anymore.

One of the faster ways that you can find on the internet, is by doing Rampage: Hellbug Extermination. This is indeed a fast way to level, it gives you 2100 exp. in around 2-3 minutes.
The clip of this can be find here: https://www.youtube.com/watch?v=PSXX2soVlPM

But there is a much faster way to level. There is only one thing: You need the Gunslinger DLC.
How to use this to your advantage? Simple!
First buy the DLC, it's not that expensive. Step one is the hardest part :D
Second you need to do the Gunslinger quest-line first, you need to complete a couple of Arena's for that, a total of 9 arena's. After the mainmissions you have to go to Overpass, in San Francisco. Teleport to the place or ask a friend with the teleport to go there and teleport to him ;)

There are 3 arena's there: The Observatory, Dark Matter Bunker and Arkfall Wreckage.
You want to go into Arkfall Wreckage.

It doesn't really matter what weapon you use for this, but I personally prefer the sword, since I one-shot every enemy. With Blur active it goes even faster, you can clear the first area without even running out of Blur!
The boss is in the second room, after you open the door, you only need to hit him like 5 times with your sword and he is dead.

Don't worry about only getting the Bronze medal. When you are in the arena alone, there will be no chance of getting Gold or Silver. Soloing this will give you 6000 exp after finishing it.
Personally I do this a lot and I can clear this arena in around one and a half minute.
If you calculate that quick, that would be: 60minutes / 1,5minute = 40... 40 * 6000 = 240.000 exp per hour! That's a lot more than the known method on Youtube which only gives you 70.000 exp per hour.

It's simple like that! Just restart the arena after you are done!

That's it. You are now ready to face your enemy.

A small summary of what you've read:
- Main & Side Missions first
- Pursuits after that
- Dailies and Events in the meantime
- Weapons will level up by using them a lot
- Gunslinger Arena 'Arkfall Wreckage' will give you around 240.000 exp per hour


Thank you for reading this guide. I hope you find it helpful. Please vote this guide and leave your nice comments below.
Good luck with leveling up and I hope I will see you somewhere in the game soon ;)