I'm pretty quick, a southpaw and have been told I have some good power. But I can't land punches consistently, other than the jab. Any Techniques for training accuracy
Well patience is the first step but of the eyes and fists not the mind i suggest Tszyu's method he trained with a head piece that had a ball attached to a string that he of course punched. Could also be you're leading with hooks and uppercuts perhaps falling short i can't say cause I ain't never seen you fight, might suggest employing a range finding tactic leave your right out (southpaw) in the fashion of Joe Louis or the Hitman find your distance and load up on bombs to the head when they go for "Easy" body shots always nice to give a blow to the jaw and take one on the body especially when your core is conditioned best you practice your drills and find what works hope i helped a little.
When you hit the mitts, focus on hitting the same spot every time. Generally there is a dot on the surface you are hitting; it is there for you to aim at. You can also use tape to make an X on the heavy bag. Throw the 1-2 at the target. You can also use tape to mark spots for body punches. In sparring, if you are landing the jab and nothing else, without seeing you, I would guess that you are using your front foot to judge your range and that your rear foot is getting too far behind your body. Those two things both contribute to your other punches coming up short.
Reflex Speed Training Ball with a Velcro headband on a long elastic rubber spring string to bounce back, and bop you in the face if you are not fast enough to hit it again before it hits you! Basically the same thing that "Sugar Footed Sam" said. You could always close your eyes, and try it that way!