I dont normally carry ords on the A-20 but here are the basics...
1) recognize that the A-20 picks up speed very quickly so you have a short dive window. As a general rule I only dive about 3k or so with power at idle on a bomb run. I prefer a pretty steep dive angle (60 degree's or so) and use the midway point between the gun sight bottom and bottom of the windshield as my "aim point". The biggest problem with the A-20 is that the combination of a short dive and limited speed often leave you in the ack envelope (I normally dont fly much over 6k when in a bombing mode).
As a general rule I'll use the A-20 as a mud mover vs either GV's or in support of a base capture as a GV hunter or to help drop the town. I generally wont engage targets at a field with the ack up since the drop puts me to low and slow. I will pickle on the town from 6-8k with no problems and normally do pretty well...then zoom back up to 10-12k and go hunting.
To me the A-20 is actually a much more formidable air to air weapon then it is an air to ground one. A jug or even a 38 is much more survivable air to ground and the 10 rockets almost equals the other 2k of bombs (except vs GV's). When I'm in a "real fighter" I'm actually a lot more worried about A-20's, mossies and 110's above me then almost anything else.
If the guy flying them is out hunting and has developed a good feel for the plane of choice (which does take time for all 3) then the combination of E and firepower creates a very difficult situation since there is not a lot of "history"....even for me. I more or less know what a high 109 or Tiffie or nikki can/will do and have a pretty ingrained understanding of the options. I'm actually as leary/confused/unsure as anyone else is when facing the above from a disadvantage. I know how to kill all 3 of them with little problem or risk from a superior position...but you simply dont just "sneak thru" an attack (especially mossie or 110) with minimal damage. {didnt mean to take this off topic}.