I have been putting a lot on the Five Iron putting green and I feel like my stroke has improved a lot. We play a form of "Golf Billiards" (the pic is from a 9-ball game we were playing) to make it fun and to make sure that there is a little pressure trying to make each putt.
My alignment has improved a lot and one thing I usually do is use a line on the ball to make sure my stroke is on the money. This might be the wrong approach for me. I came acrosss this interesting video form Dave Phillips and Greg Rose discussing visualization skills and an easy test to see how yours are.