Start out slow im not saying camp but use an assault class and try to stay in a general area after you get the hang of that expand your area and try to stay alive as long as possible without getting killed or camping. Finally once you are good at that switch to an smg. Such as the p90 scorpion and mp5 restart the process. Keep expanding your area until you can run around the entire map. Now the perks vary on what gun and what game type( as in HC and Normal) A solid perk set up for normal is Bandolier, Stopping power and deep. If you get killed alot I would recomend Marty but its kind of noobie and not allowed on some servers. On HC 3 nades/Bandolier, sleight of hand, and deep. Hope this helps
Happy Gaming, Lumen
P.s I have seen you play in game, you will get better as you play. Just ask some people for stratagies and you'll catch on fast. So just keep playing!