[Dr Kain]

I was looking at the 100% checklist and I don't think I would ever be able to 100% this game. There is just way too much stuff to do, plus, I have never beat the mission where you have to shoot down the RC Barons that are trying to blow up the nerd's towers even with using the cheats.

[miromiro]

Take a plane and practice with it. Take a look at this topic. It'll help you understand how to fly. The thing that you also might find hard at the game are the collectables. But, there's a tool called SAMA (San Andreas Mission Analyzer). It'll tell you where to find those collectables and everything you've got left to 100%. We also play a game called Chain Game. We take a save file from 0% to 100% without using cheats. This way you could practice your skills with the game. You can find the topic here. Good luck.

[lil weasel]

"Air Raid" can be done if you watch the patern of the Fokkers approach. They ALWAYs follow the same paths. Once you get the pattern down it will be easier.
Center, Left, Right, Behind CJ.
Don't shoot all the time. the gun vibrates too much. Swing the aim point in front of the approaching plane and then trigger the gun.
In a couple of cases when the four planes are in line just let them fly into the bullets, just like real life.
Don't Chase the planes you can't catch them, they have to fly into the bullets.