Early in the game, you might find yourself with the opportunity to place an expendable destroyer squadron (Cobras work best) facing directly into the enemy, at 60-70cm range. Put them on AAF orders and launch a point blank spread of torps if you get the first turn. The enemy will not have the chance to launch any fighters or ordnance of their own for defense, and the early cripple or kill can swing the game your way. The Cobras probably will not survive the experience (though I've seen them skate free), but at least you will have a chance of a cheap early kill. In fact, if you can line up a couple of ships/squadrons, you can maximize your fire even more.
The more I play Imperials, the more I find battles begin with the fleet on AAF, launch torps, then go on reload or Lock On (or Burn Retros against Eldar!).
Making a run like this works especially well with Imperial ships, because of their large torp armament, but Chaos can use it as well. You can use it with the Dauntless torp armed variant, but the Cobra goes further (30cm move + 4D6, average 44cm, vs. 25cm + 17cm = 42cm) more reliably.
--T. Ray