On a scale of 1 - 10 on general realism I'd rate myself a 9 or 8. But when I attempt parkour I just completely fail. I fail usually because of running in the wrong direction, falling, or lack of momentum and it doesn't help that they usually look ugly. Help me

This video covers everything from the basics to the very advanced stuff, talking in-depth about which joint gives you momentum, slows you down, keeps you on or takes you off balance.
Try to give it a shot and lots of patience.

This wasn't a tutorial, so I've move it for you. Speaking of tutorials, some that might help you: How to Spar, Sunny's Realism Tutorial