I'm sure most of you know this already, but I just discovered it a few days ago and am still thrilled about it.
Pressing the "Z" key will delete your last stroke.
Before I knew this, I was erasing 20-stroke characters because I messed up stroke #18, and oh what a PITA it was to re-draw the whole thing. No more! Simply hit "Z" and the offending stroke is a bad memory, while the other 17 remain in their pristine original condition!
Just thought I'd share.
頑張って!