Other than downloadable skills, I think it's just practice. I must say that when I first started playing I thought I was going to have to go back to Bad Company 2. Then, I realized I was doing better
Just gotta figure out what kind of setup works well with you and slowly branch out from that. Also, watching online videos seems to help because you get strange new ideas and see what other people see in game.
As for Red Bull.... Take it from me- a guy who had a heartattack at age 20- don't do that!! lol There were a couple times when I drank 9 Red Bulls within 2 hours. Not a healthy plan
Oh I wish my footage of plays wouldn't take so long to gather. Last night I spent an hour on an empty Caspian server filming the undamaged landscape, then destroying everything around and then filming it when the antenna fell and broken. Not looking forward to sifting through those files later.