I occasionally practise in front of a mirror. And promise - that's not because I think I am particularly pretty.
With this method I was able to even out a few problems in both hands in the past.
Just recently I came across an app for my iPad that provides a good alternative for me now. It uses the camera to record and replay with a configurable delay. This means, I play a problematic passage of what I am practising and a few seconds later I watch what I did right or wrong. Advantage for me is that I don't have to correct my technique simultaneously when playing. Also I don't have to arrange myself in front of the mirror in the bed room.
The app is called "cu-q" and was probably written for ladies who want to marvel at their new hair style. But for me it does the job studying my hand motion.