I honestly always though Raph was the worst Turtle. Mikey I always thought was pretty good, even thought I'm only somewhat good with him.
In order to be "doin' it and doin' it and doin' it WELL" with Raph, again, the basic thing was to think "CE Bison", with a few alterations:
Annoy people with your weak, yet very fast and high priority kicks, use your very good drill when the opportunity presents itself, and his projectile works well with his overall game. You won't be able to Hadouken-spam too much with it due to start up time, but there's no lag afterward. Don's projectile IS faster, but the bo-using turtle's also has quite a bit of lag on the back end, PLUS his hitbox is extended (due to that bo!). That's the kind of thing that a seasoned Raph player should just "Chest Buster" and turn the tide in his favor.
Then there's Raph's Super. Easily one of the best in the game, because it does good damage, whether taken to the face, or blocked, meaning that it's pretty good to use as soon as you get the meter for it.
Also, like Mikey, Raph has set-ups that can lead to 100% Stun and 100% Life combo. You'll likely never get it off against a good opponent, but if you can, you'll make the opposition pay for their mistakes.