Learning to not get hit is the first step towards getting more hits on your foe.
Strafe like hell, and maybe map vertical strafes. Perfect the timing of your engine kills.
Once you've got them down, you've only got to shoot the other guy. And that isn't too hard, unless you're a bomber pilot.
Also, remember that there are different methods of taking out different ships. Taking a fighter head on is my favoured approach, but I will never do that to a bomber (again...).