Stay fast, go in at about 12k.
Ignore these jackoffs, drop your bomb-bay bombs first, otherwise a steep turn will rip your wings off. If you empty the bomb bay, you'll be able to turn better than ditching the wing bombs.
The little triangular thing supporting the gunsight gives a good cue for shallow-angle divebombing.
The A-20 is fast. It's speed is its main defense. But don't be afraid to mix it up a little bit once you have dropped your bombs. The A-20 can turn well enough to catch people off-guard. If you can convince someone to ride in your turret, great, but don't try and use it for defense unless you're shooting at someone who is far enough behind that they can't shoot ya. When they're that far behind though, a good trick is to get into the turret, use your rudder to keep them in your gunsight(Without turning TOO far) and crack off a few shots at em.