Editing is my friend - I've done a lot of podcasting, so I'm okay at avoiding a lot of filler words but I still find myself saying "um" way too much for my liking, but it's easy enough to take em out in Audacity. Practicing really does help such a lot (I'm pretty confident when I have at least one other person to bounce off on a recording, but doing a single person LP is pretty challenging for me), as does listening back and critiquing yourself, then focussing on not saying the words you're wincing at next time.