Hi and welcome to VGR. First, I'll move this to the Video Games Sub-Forum as that is section to discuss specific games.
As for the topic, I'm not much of a Battlefield fan, but I can say with some confidence that success in those kinds is game com from teamwork and practice. The main difference as far as I can see between COD and Battlefield is the team size, so if there's something you need to adapt to, I'd say it's that, but I'm not an FPS expert in any way.