@ElectricPaladin Being more noobish than both previous posters, I can attest to the fact that for my first games (Honestly, probably first 10 or so) I found torpedoes to be really lackluster. Really did not like them, and I played IN same as yourself. Not that much has changed, but I find myself commonly doing this: firing a volley on the way in, which forces the opponent to split, take it like a man, or use defensive ordnance. As you may have noticed, IN do not have quantity or quality when it comes to assault craft. The only thing going for it is synergy, as in lots of torpedoes alongside AC. If you launch torpedoes early, you can force your opponent to use some of his to counter...which can go along way towards not being locked into a defensive posture the whole game.
So basically, I fire once early while going in, then keep 'em loaded to stop opponents from crossing my bow for fear of shotgunning. If such an opportunity arrives, use it. Torpedo escorts are a little different; if it has 1 torpedo, such as a falchion, I tend to use them for a defensive role only, freeing up my other ships a little. In the case of cobras, it is very easy to outflank an enemy; it is probably the easiest torpedo skill to master, and as AndrewChristlieb pointed out, a very effective one.
IMO they were the hardest weapon system to learn how to use correctly.