I practice with my strong arm and weak arm, full extension, in close, oblique angles, things like that.
I also make sure that my holstered weapon is in a location that it can be pulled with my off hand if necessary. I always say that if the time ever came for you to have to defend yourself and your family started off with you being shot in your dominant arm; it would be terrible if you couldn't draw or effectively use your weapon with your off hand.
Alternate method is to keep your primary weapon in a strong position, but keep a backup weapon accessible to your off hand.