Focus on playing the objectives and your score will improve the most
To improve your KD, it's not about getting more kills, it's about dying less. Learn to stay alive. That means after getting a kill, back up into cover, reload, heal up, reset and breath for a second, then go re-engage.
Positioning is King in any shooter. Learn to give yourself and find the advantageous spots around the map. When someone is firing at your from a spot that you can't seem to land shots on them, remember how they used that cover. Your goal is to try and put your enemy at a disadvantage. You want to make gunfights unfair if you can.
Use meta weapons, and find a build that works well with you.
There's a ton of nuance and practice that goes into getting better at shooters. It takes time. Just build up routines and learn certain structures and how they play.
Try not to over extend and rush without support. Try to die near cover so that you can be revived. If you die out in the open, it's much harder to reach you.
Hope that helps a little.
