Taking it slowly is the best advice. Practicing with a butter knife may work but it's not exactly a razor. You might consider picking up a very cheap blade such as one of the Pakistan razors for $4.00 or $5.00 on eBay and then dull the hell out of it with sandpaper. You might even put electrical tape on the edge and practice with that. As for the nicks in the strop, I've had some luck with contact cement. Just be careful to get it only on the areas you want to stick together. Good luck.