A couple of techniques I use:
Low-level shallow dive bombing
- get close to target (almost on top of it) at ~2,000' and stabilze the dive at 30-40 degrees
- when target hits the part of my plane (usually the gunsight frame) I drop the bombs; usually at around d800 for a GV
Mid-level dive bombing
- get directly over target at ~7-15k
- pull straight up and cut throttle
- let plane get close to stall and roll over nose-down
- make small adjustments to aim on the way down
- drop bombs and pull out before compressing/augering
I don't spend much time dropping bombs anymore, so I know I'm a bit rusty at it and these may not be the best techniques but they worked good enough for a turn-fighter like me.
It's all about picking a plane and practice, practice, practice...until you know the sight picture for proper setup and how everything should line up when it's time to drop the egg.