Online is fun, especially on large maps. You can virtually run around and learn how to do stuff without a whole lot of attention being called to you (ala people bitching cause you are a noob). They will only grief you if you hop in a plane or helicopter then crash right away.
I use to do that just to piss people off. Sometimes, people spend the whole 30 minutes, or 60 minutes in a plane or chopper, they don't get down on the ground to help capture flags, and that pisses me off. So I'd throw all my C4 packs on the plane, wait for the "lone wolf" teammate (who thinks shooting down 2 planes in a 30 minute match actually helps) takes off in the f'n thing, then detonate all the C-4, disabling the plane so he's gotta bail.
I'd say, play the single player campaign to get use to the controls, then try MP. You might do better than you think. If I had the PC version, I'd jump on there with you, but I only have the 360 version. Sucks cause I could teach you the ropes on it.
Regards