Sorry you're first try got nixed, hopefully you'll get another stab at it. Until then, I got to thinking of a few other tid-bits that might be of value to you that don't often get mentioned.
1) ALTITUDE - There is two different altitudes to shoot air-to-air at, either high, or low. It is really easy to plan to shoot at 2000' or 3000' agl because that's where most people fly. That's exactly where you don't want to shoot. That is where the haze is the greatest, and the clouds are the worst. I plan to either shoot low (500'-1000') when I've got great backgrounds, or high when I've got great clouds (or if that is the environment where the airplane really belongs). Here's a couple of examples:
High (this was about 10,000' I think):
Low (about 1,000' agl as I recall):
2) BACKGROUND - If you are shooting something with the background being really visible, (such as the "low" shot I have posted above) you really want a clean background. I've shot over cities (the worst), trees (decent, but still busy), open fields (getting pretty good), water (really good) and all sorts of back grounds. Consistently I am the most pleased with the simplest backgrounds.
3) FLIGHT PATH - This on is a little more complicated, but it is a really important one. Jay hit briefly on it when he talked about flying "race tracks." Once you determine a "light line" - the heading that gives you the best light, you've got to figure out what to do with it. Flying race tracks as Jay suggested works well, but always puts the airplane in the same turn when you are "on the light line." Flying straight on the light line also works, but takes up a lot of real estate and gives a very plain, boring straight and level shot.
What I do is start by establishing the "light line" heading, maybe 180 degrees. Then, make about a 15 degree bank, 45 degree left turn (to a heading of 135), then turn right back 90 degrees (or 45 degrees right of the light line), in this case to 215 degrees. Continue this "S" with the target airplane in several positions (maybe a high position, a trail position, a low position...). This gives you good light on the airplane in both a left and right bank, shooting down at the ground and up at the sky. Works great. Your flight path should look something like this (the red line is the optimal light line heading).
|/
||
|\
| |\
||
|/
/
||
|\
|Those are my last few thoughts. I'm sure there are more, and this is probably too much information as it is, but I hope it helps you some. I hope that you are able to get the shoot done and you'll definitely have to post them when you get 'em! Good luck!