Hey guys, I don’t know if i’m bad but I cannot get any kills. People move so fast and I’m generally good too but I cannot aim at them and somehow they aim at me and get me. Are there any tips, should i use a controller, which sensitivity? Thank you.
Can't get anyone
Go into settings and turn on Hitsounds. It will definitely help improve your aim. 
If this is your first FPS, welcome to the slaughtergouse.
^ Do turn on hitsounds, I don’t know why it’s off in the first place.
DO NOT USE CONTROLLER, unless you have been using it for your whole life up to this point.
Admit you’re bad, if you know it is true. Only when you do that can you get better.
Try to tapfire instead of spraying. Recoil and spread can screw you over in a firefight.
Turn up your sensitivity, or maybe even down, this can lead to over or undershooting a target.
Change your FOV, or Field of View, to something you are comfortable with.
Dirty Bomb is a very fast shooter.
You will adapt to the speed of the game once you have played enough.
Here my hints.
Sensitivity:
Even though it’s personal preference which sensitivity you feel comfortable with, perhaps it’s easier for you to determine it by knowing that most players are using a sensitivity from 1-20.
Don’t forget that you need a bit of time to adapt when changing it.
Graphical effects:
You can also try to disable all the graphical effects (shadows, light).
I know that it looks awesome but there is nothing more important to see than your enemies.
A config data could help too.
I downloaded one and I’m happy that I did - I notice enemies a lot faster now.
Sometimes you just have a bad day or need a break.
Play something else in the meantime and then come back.
Other than that there are only three words to say:
Practice, practice, practice.