ill state the obvious-> take out shield generators with bombers and the shield drops
its simple but very effective, especially against piet
i also, when rebel, use fleets of fighters, bombers and long range missile boats in hit and run raids which work. Whilst this tactic doesnt involve new information about ships i dunno how many of you have tried it, its quite good. 20 x wings and 12 bombers can decimate a fleet many times their worth.