At the very least, whether you get any kills or not, being in the capzone is the priority. Nearly every RO map is winnable by capturing certain zones, and without people in those areas, they will not get capped. All too often you watch people hiding outside the capzoznes trying to pick people off one at a time. Thats a nice effort, but odds are that person you spent 30 seconds or more killing will be replaced quickly by another teammate. There's nothing more irritating than watching a temamate empty 1 or 2 magazines from an MP40 at someone 1-200 meters away, finally getting a lucky shot for the kill if he even hit anyone at all.
To start off with, I'd say go the polite route and stick with the rifleman. This will get you used to picking your battles, using cover, and using the aiming and control systems in the game. You will notice that the average person, someone whose played the game for at least a few months, is grossly outmatched by the SMG. The reason I call this the polite route is this- taking a specialized role and not being good with it right away earns you a lot of hate. Starting off with an SMG or STG you will quickly find that it is much less controllable than the rifle, and until you are experienced with the games mechanics, it is best left in the hands of someone who does know how to move about the maps and fire them controllably.
It kinda sucks in the mean time, but learning the maps as a rifleman is just an easier way to get into the game. It saves you a lot of grief from impatient players, and helps you understand the importance of cover, how to aim, and how to move to the capzones and win. It seems like there are some here who don't like to read that there are new players in this forum, so feel free to PM me if you would like, I can point you to some forums that are more accomodating to beginners.