Are you visiting Rob Pilger at his site, http://www.boxingperformance.com, and following him at Facebook, Twitter, YouTube, and at his syndicated news feed? I hope your answer is "yes," because if it isn't, you're missing a lot. He offers some serious training content.
Here's a recent example. You've already learned that punching power comes from the base of your body, all the way from a floor. Here is a video of Rob Pilger explaining that principle a lot more effectively than I can, complete with demonstration of proper footwork.
I have the "fast feet" device from Ringside that is shown in the video. It helps me keep my stance from going too wide and prevents me from some of the more awkward positions that clumsy footwork can place me in. If I am in awkward position, I am off balance. If I'm off balance, something as small as a good shove to my shoulder can push me over.
This video is just one sample of the content Rob Pilger produces. Of course, he doesn't need me to persuade you; just go to the site and look around: http://www.boxingperformance.com. Most likely, you'll be a regular visitor after spending just 5 minutes there. Enjoy!