Like zilla said, the way to go is to practice on an empty server. But almost anyone will tell you that you'll get more kills as gunner than you will as pilot. Granted there are some pilots that are really good with their missles, but the best killer in a chopper is the gunner with the cannon and the tv missles.
If you're no good on tv missles, most pilots won't want to fly with you. I would suggest getting a friend to play with you and get on an empty server together. If he's a decent pilot have him set you up for tv shots, if he's not any good you should both practice flying...then practice gunning once one of you is good enough to fly for the other. Practice taking out targets like FAV's, Humvee's, boats, etc. with the gun. Practice taking out targets like tanks, apc's, and enemy choppers wtih TV missles. Of course these will all be non-moving targets on an empty server, but it should help you at least get a feeling for the weapons.
Also, I would strongly suggest getting a joystick to help with the piloting. Many people prefer to fly with the keyboard, but if you can't do it get a joystick and practice with it for a few days and you should get it.
TV missles are easy enough to figure out but you definately need to practice if you expect to have any consistant success with them.
Also, a big help is using teamspeak or VOIP with your pilot/gunner. If you can talk to each other you'll be a much more leathal team. If you'd like, I'll go on an empty server and practice with you. I'm a decent pilot and a better gunner. It's always tough to find someone good to team up with so if I can help, send me a message.
Hope this helps.