Avoid the high noon sun shots. Cameras can give a false reading and light conditions can be deceiving. Classic examples are a white airplane on a black ramp, black or dark green aircraft on a light coloured ramp, or either with snow banks in the background. You want your subject to be well lit by the sun. All the above points are for straight non-moving portrait shots of aircraft.
Cameras are like stereos.
You get what you pay for. By far the most important item is the lens, just like the speakers that come with your stereo. Having a camera that uses interchangeable lenses gives the shooter the best flexibility possible. Several lenses may be useful. In my opinion, a fixed 55mm is great but a zoom that covers 35-100mm will probably serve you best around aircraft.