The greatest pressure putt I made in my career was on the 72nd hole at the first stage of Q-school one year. It was a 15 footer for eagle and I needed to make it to make the cut to 2nd stage on the number.
I remember very vividly how I made the putt, it was 14 years ago and still to this day I try and duplicate what happened on that putt, with varying degrees of success.
I read the putt and as I was standing over it, I visualized the ball rolling along the line and breaking into the hole.
It is still the most vivid visualization I have had to date, but the better I do this, the more putts I make.