Moving the ball back is a good idea for that kind of game. Put a little cash on it too, and those second putts have got some real pressure.as much as I support and encourage the idea of practice, I think the first and most important thing to do is learn proper technique in putting. If you don't have good technique, you may still really struggle on the greens and that could cause a lot of frustration when you put the time in to practicing.
When I am alone I focus on two balls from pretty much any direction or angle and work almost specifically on direction and strike quality.
With friends, we play a game where you pick a hole and putt to it, but if you don't hole the putt you have to back the ball up a putter length and continue putting. It removes the tap in opportunity and really forces you to make some knee knockers. It's pretty fun.