#1 Why are you taking photos? If it is for your own enjoyment and recreation, have at.
If youare doing it because it is "cool" to have photos on this site (or any other site), forget it. It can be too frustrating and the learning curve can be steep for the high quality this site demands. (and the other big sites are also demanding, tho perhaps not as much as Airliners...)
#2 There are a couple of nice articles on airplane photography here on this site. Read them. Page through the recent additions to this site so that you know what level you want to achieve. Look at other sites and see the type of shots there. Learn what looks good and what does not.
#3 If you know nothing about photography take a class at school or a Jr College on photography basics. Pick up a book at library or book store on photography basics. Kodak has a couple nice ones out and I like the National Geopgraphic Photographers Field Guide. Basic and common sense without lots of technical terms.
#4 Go out to the airport and HAVE FUN watching the airplanes. Take lots of photos and then compare them HONESTLY to what you see posted here. If you have the ability to link some of them to this site through your own web page do so and ASK QUESTIONS. The ones titled "Help me with this" tend to get lots of good responses.
#5 Stick with a quality SLR or Digital camera. You don't need to have a big bucks one to take great photos. But you do have to learn how to take great photos.
#6 ENJOY YOURSELF!!!!!