My advice would be to attack from dead ahead. Even when your attacking an operational CV, even if you attack from a distance then you will have a much larger chance of hitting something. Also if you are flying the JU88, then use the formation option. It gives the CV more to shoot at and you a 3 shooter instead of a single shot
That is the best way to hit something but if you wana do some serious damage you need a formation to do a side attack on the ship, this way you are going to get 3 torpedos to hit the ship and you are going to really do some damage.
As Ghosth said, lots of lead and a whole lot of practice. After you have done it a few dozen times then you will be able to do it blindfolded while playing poker:D
Last piece of advice, get low, and when you think you are low enough... Go lower.
LOL, oh yeah, last one i promise. When you drop, don't try to overfly the CV Group, do a shar 180 and punch the throttle.
BT