I'm an online n00b myself but I haven't had too much trouble...look up combat flight tactics on google....here's one:
http://library.thinkquest.org/3142/manuv.htm
so many classic scenarios seem to play out online...if you recognize them you'll at least have an idea what you should have done when you get killed
the one that has got me the most kills is a properly timed initial turn...and stick with a plane you like so you get used to how it handles and how much you have to lead targets.