My advice (pretty worthless I guess):
A. Get Shaw's Fighter Combat. Read it. That will give you the vocabulary to analyze what you're doing.
B. Fly a lot, but analyze what you do:
1. Find someone else and duel. After the duel, evaluate each other's performance.
2. Do the same with a squad. 2v2, 3v3, whatever.
3. In the MA, fly with a wingman, or a squad, and after each sortie, analyze what worked and what didn't.
4. Fly TODs, campaigns and any of the other "historical" events. Keep the film running. Afterwards, evaluate:
a. your performance. What did you do? What didn't you?
b. your squad's performance.
c. your side's performance.
now go look at the film, and read the AARs. Post one of your own. Don't be afraid to criticize. If nobody tells me what I'm doing wrong, I won't improve.
Every time you get shot down, it's something you did wrong. Figure it out.
C. Some practical tips:
1. Study the performance charts of the planes. Where are you most competitive? What sorts of tactics should you use?
2. Dogfights are won with ailerons and rudder, not the elevator.
3. Work up a couple of good defensive moves. A high bandit screaming on your six puts you in the same position as a pitcher in baseball. You have to pitch something, and he has little time to guess what it is. If you have one good move, you'll beat most of the minor leaguers. But if you split ess on every pass, even a rookie will be able to guess what's coming and anticipate it.
Pulling slowly vertical is a "fat pitch". Don't hang those curves.
4. Offense: I can't shoot, so I can't tell you much.