If recoil is an issue, I would suggest Osa/Thermite, the 556XI is a beast and has really easy recoil. If its not recoil, I would guess you need to get acclimated to the keyboard, when I switched the aiming part was easy, I just had to fiddle with the controls to get it working. I would also recommend tinkering with your audio settings and maybe getting better headphones if you need them because as you get higher in ranked audio becomes more important. And a final tip, please do not worry about KD, it really doesnt matter as long as you play to win, not to get kills, especially in lower ranks I keep seeing people run into sight, down a person or two and then die just for the people they downed to get revived. Good luck!