I love taking the Devestator in for a dogfight. One shot with the plasma gun, and the target's toast. Plus it's got a Stormfire for a little extra range. Not the most maneuverable, but the forward firepower and all those turrets make up for it. Anyway, my tactics are:
Broadsword-Make the first pass with your Mass Drivers, then stay out of flak range of your target, go to full speed, then rotate through the turrets to keep the fighter in sight. Sometimes, you can also go for torpedo lock, while using the turrets, but it's usually best to clear all fighters.
Crossbow, Longbow, and Shrike-Keep on the fighters till they're gone, then head for the capship. Use whatever missles you've got.
Devastator: You can either dogfight, or just head for the engines of the capship. All those turrets on the Devastator can keep the enemy honest, and if one comes at you and doesn't break off, just swing around and hit him with a plasma shot. Blow up the capship or base, then head in for a dogfight.