Success in B-17 revolves around taking care of and learning from your crew. Take time to notice how the computer-controlled gunners aim for the fast moving fighters and try to learn from their techniques.
Fuel leaks can be critical to the success of a mission.
If necessary you need to turn off an engine or two and drop out of formation to conserve fuel. Keep at least one pilot healthy because the plane can end up in a spin if it's in a turn when the pilot is hit, giving little time to bail out. Make the radio operator send a MayDay message to improve your chances of survival when you're bailing out over the channel. Bail out over the channel to ensure mission success. Before landing, attempt to heal injured crew otherwise they are hospitalised.