Mirrors are handy tools.
If practicing before a mirror you need to evaluate where your point of aim is for each "shot". Most of us will likely start off pointing low -- bellybutton or belt buckle. Not that this is a bad place to hit someone, actually, though you want your shots to be COM. Just remember if a real aggressor is taller or shorter your "muscle memory" will be slightly off.
Practice looking at your ("opponent's") face during the draw. Not so much to get that "Tough Guy look" but to identify your opponent. This habit may save the life of someone you know.
Mirrors can be tactically advantageous too. Placed in the correct spots around the house they'll let you know what's around a corner. The caution is that they work BOTH WAYS. If you can see the BG, he can see you. Another idea is to hang glass covered artwork on the walls in key spots so that you can take advantage of the subdued reflections off the glass.
BillCA in CA (Unfortunately)