Institute for Legal, Legislative and Educational Action
One of the most eye-opening experiences I’ve had in terms of training for handgun self-defense is the realization that square range, two-handed shooting techniques almost never comes into play in close range defensive encounters. Your support hand might be in use attempting to pull a family member behind you, block an attack, etc.
Aaron Cowan of Sage Dynamics gives some great advice on how to work on your one-handed shooting skills.