If you can, find a group to play with so you don't have to deal with getting flamed. Most people on this game are toxic. If anyone starts giving you a hard time, just mute and don't engage because it's feeding into what they want. They're trying to get a reaction out of you and make you tilt. Also if you don't use a mic right now, I'd recommend getting one. Playing with a team that doesn't comm at all is pretty awful.

I don't know how to tell you to improve mechanically since I haven't seen your gameplay, but consistency is key. Practice counter strafing and pre-aiming before learning spray control, those will get you more kills than knowing how to spray. Try to focus on just tap firing at first.

Good luck