As with anything, photography is something you get out what you put in. Not sure what kind of camera you have, but practice makes perfect. If you have a digital camera, you can also practice on the cheap. Start out with ramp-style shots, maybe thru a fence or glass, unless you have airside access, which does make things easier.
I think it also helps to have a favorite "style." For me, I really like 3/4 angle shots. Here are a couple of recent examples:
If you don't have a favorite, browse the excellent picture selection on this website and see something you like, and then go try it.
If you want an excellent
book on airplane photography, check out Airliners in Flight
, it will blow your mind