Shoot in bursts. Holding the trigger will only get you killed and have you chasing the muzzle.
Slow down your gameplay. COD is very fast paced, battlefield has much more strategy, teamwork, and objective focus. Don't worry about your K/D. If you play the objectives you can help out your team, earn MUCH more xp and rank up faster.
Stay out of helicopters until you play co mission "fire from the sky" several times.
Play with groups of 4GC and the transition will be much easier as you can get help, tips, learn strategy, etc. If you jump in alone the transition from COD can be quite abrupt.
I'll send you an invite.