When running around use the barrels as an advantage. You can prone near the barrles, then wait until the oppenent passes by, get up and kill them. The class I always use is mp5 w/ silencer, 3 frags of stun, stopping power and steady aim.
once you get the UAV you should win...
- p90 red dot
- bandolier (you will most likely not die, so u will need the amo)
- stopping power
- dead silence (when people play 1v1 they are usually good and have a professional headset, they cant hear you no matter what if you have dead silence)