First, flexibility. Wanna do this? You'll never get electric-chaired again, Jonathan :)
Found on Alliance Atlanta's post on PNF stretching. PNF stretching after you work out is the way to go, from what I have read and seen. I will add, as Dev pointed out, that PNF stretching can be dangerous, too, so it's not for the uninitiated or those working without guidance. I'm lucky, I train in a "regular" gym with sports med people all around, and I have a great academy with doctors, physical therapists, personal trainers and massage therapists too, so I'm always being watched.
Second... from Liam's blog The Parttime Grappler... some really stellar advice. He has lots of other pieces of the puzzle in his original post, but these three are key for me and the last one? When I fail it's here.
# Always ensure you are in the best possible position before launching your submission.
# Always ensure your opponent is in the worst possible position before launching your submission.
# When mid-submission you sense your positional dominance slip away, abort the submission and work on regaining your superior position.