Well i only started playing COD4 like 4-5 months ago.. so im still farely new and i only started playing the game hardcorely like 2 months ago... and i would say i have improved tremendously since.. im more of a close range SMG user.. basically the ak-74u along with bando, SP and DI and i trained with the gun for almost a month and i find myself alot better then b4. especially at close range.. my tips would just be to find a gun ur comfortable wit and practice practice pratice.. not only on pub servers though.. im also a pertty decent sniper and assault user.. just dont really fancy those guns much.. just my 2 cents..

cheers!!
[H2o].D3atH