Attacking a bomber alone in World War II was considered suicidal. You had 10 or more guns pointed at you so it was a dangerous risk you took enganging any bomber.
In AH, we can't always attack a bomber with 10 of our buddies so there's some strategies you can use.
A) Always gun in and fly out. Don't stay around the bomber for long.
B) Dive in from the top on any bomber so it can't train more than 1 gun at you.
C) Find a part of a bomber where there are no guns. (For IE, the 26 and Lanc have no belly guns).
D) Go for the planes engines, taking a wing or engine can decrease the time you have to stick around with the bomber.
E) ALWAYS run if you can't stay and attack. Running isn't cowardly if you have a meaning of doing it.

Hope that helps.
Onnie Mcyntire The 332nd Viking Squadron