Your learning curve will go up as soon as you learn the maps. I find that I do better sticking to the outer perimeter and hug walls so that my attack field of vision is only about 90-180 degrees or so. Also, I rarely run unless I'm running away from something or getting across the street. With as many passagesways and corners, I get alot of kills because I can pull up my sights faster than someone who has to disengage from running before pulling out his gun.
M16 or SCAR with FMJ and Holographic
Thats something I have noticed lately. I used to run a lot but i kept running into campers or people with better weapons who could fire and kill me before i got two shots off. The slow movement. find a spot get a kill and then move on seems to work well. I'm still trying to get my weapons sorted. I have the thermal sight for the scrah (?) but its only good over a short distance.
Awesome game though. The only thing I dont like is that the malee knife is unrealistic. Its far too effective and a long range. by that i mean a couple of foot when 2 shots of a shot gun might not kill them at a couple of feet!!?!???