Assuming I haven't developed any skill with specific weapons yet, what weapon skills should I develop. For example, if I were to become a master with a sub-machine gun, would I typically still get owned by average players with assault rifles?
I suspect the answer is some variation of "it depends", but certainly some weapons are almost useless in the hands of a noob.
No one can really tell you. All of the guns are suppose to be "equal" but in their own way. You wouldn't want to use a sniper rifle for close range(quickscoping isn't that easy!), nor would you want to use a submachine gun for long range.
How do you commonly play?
Personally, I like to run and gun. I stay still very little and prefer close range combat. As such, I usually use the submachine guns and assault rifles.
If you prefer to stay back and pick people off from range, you'd probably want snipers and assault rifles (maybe with an ACOG).
If your accuracy is sub-par, you may want to spray and pray by using a large machine gun with a 200 bullet clip.
The main thing is, just try out all sorts of different guns and perks. No one can know what class is good for you except for you.
You can't really compare how one weapon (or class of weapons) would fare against another weapon head-to-head because you're going to play differently depending on the map (and even your style of play).
That said, I think there are some weapons that are a little easier for more inexperienced players to develop their fundamentals on before discovering their own game play style (or these are weapons that made it easier for me to go from total noob to almost average).
Perks:
Quickdraw and Stalker
Assault Rifles:
SCAR-L (use the M4A1 before you level up to the SCAR-L)
Fairly clear iron sight so you can save an attachment for something else and not worry about being EMP'ed, fire rate isn't as fast as other AR and it's got a smaller magazine, but it's got power and it'll teach you to pick your shots and not spray like nuts.
Sub Machine Guns:
UMP45
Very clear iron sight, fire rate isn't as fast as other SMG's, but it's accurate.
Light Machine Guns:
MG36 (use the L86 LSW before you level up to the MG36)
IMHO, the MG36 feels like an assault rifle, but still has same punch as an LMG.
