On all levels that contain multiple aircraft bogies, the best solution is to wipe out all aircraft by flying low to the ground, then pulling up on the stick to get a missile lock to destroy them. Take one bogie out at a time, then fly back close to the ground and start the process all over again.
Flying close to the ground causes the anti-aircraft guns to overshoot your plane. They cannot fire below a certain point due to the risk of hitting their own men.
While speed in completing missions, extent of damage to your jet, and "First Blood" bonuses help, they will never allow you to gain the points and medals to open new jets. The key to points is ammunition choice. Try to use only guns for everything, saving all the missiles and bombs possible. If you must use missiles, use the self aimed, not the guided. The more bombs and missiles you return with, the higher the scores. By doing this it is possible to advance from the normal 300,000 to 400,000 red star success to consistent scores of over 2 million per mission.
As the missions gain in complexity, every fly over must be highly efficient. Instead of tight sweeping turns, use over-the-top turns. This can cut a 10 second turn down to 3 seconds and place you in a better attack mode to start the next run. This requires practice.
Use the afterburners when you are close to the ground. Note: This will not work on BTROs or gunboats (it will just do damage).