With our image library growing by leaps and bounds, I thought I would share a few tips for taking aerial photos. I know other IANites have been on overflights too, so please chime in to expand this list!
1. Most importantly, you need good weather. Sunny, clear, with as little wind as possible. Summertime is usually a bad time to take photos, as the humidity and haze reduces your visibility. Spring is a great time to do it, after the trees have leafed out. Fall is also nice, those crisp days allow for unlimited visibility and the leaf colors add a nice touch.
2. Use an instructor from a flight school. Most regional airports have flight schools that will be happy to take you up. Two hours is a good timeframe. Make sure they use a plane with wings mounted at the top (not the bottom), so they don't obscure your view. Also ask them if you can open the windows while flying - this allows for clearer photos as sometimes the windows reflect the passengers in the plane.
3. Use a four-seater plane, allowing for three passengers. Make sure all three passengers have cameras, so that you can get photos out of both sides of the plane.
4. Take some motion sickness medication before flying if you are prone to motion sickness.
5. Try to take photos at an oblique angle (not directly downwards). This allows you to capture much more of the surrounding landscape. Downwards photos can be useful to capture specific things, such as a seagrass bed or a particular land use.
6. Make sure the horizon is, well, horizontal. This means keeping the camera straight and not at an angle.
7. Make sure the flash is turned off (it is useless when taking landscape-scale photos, and will just reflect off the window), and the highest resolution settings are used.
8. Take along spare batteries and memory cards.
9. As soon as possible after the flight, download your photos and include as much metadata as possible. Sit down with a detailed map of the region or use Google Earth to record as many details of each photo as possible - direction photo was taken, landscape features, town names, waterway names, etc.
I hope that helps!