As with all shots, visualizing what you want the ball to do is much more important that many realize. It isn't enough to simply look passingly at the hole and line, actually 'see' the ball, rolling at the speed you want, on the line you want. Let your eyes track that line back from the hole and then make your stroke without delay.
Aside from that, keep a steady head, follow through, and hold your finish. Sounds simple, but most folks don't do it, even when they think they are. Don't look to see if you made it, listen for it.
__________________
"Support the On Plane Swinging Force in Balance"
"we have no friends, we have no enemies, we have only teachers"
Simplicity buffs, see 5-0, 1-L, 2-0 A and B 10-2-B, 4-D, 6B-1D, 6-B-3-0-1, 6-C-1, 6-E-2
Once you have yourself a reliable stroke that works...
1st....make 100% sure your aim is perfect on every putt....pick a little spot on the green 6 inches in front or w/e....roll the ball over it.
2nd....try using a Clear Key over the putt....w/e it is....some song in your head or w/e....it'll keep your conscious thoughts at bay while you're hitting the putt. Stick with it for a while if you're gonna give it a shot....it takes a bit for your "system" to get used to it so it works to it's full effectiveness.
Taking it to the course revolves around The Computer. Read the putt without omitting any of the slightest details. Visualize that which you want to happen. Press the "you" button and let it go.
Taking it to the course requires proper "mechanical practice" and proper "playing." Perpetuating the thought of putting being simple only makes it more mysterious and complex.
Practice with Purpose. Play with aid from the Computer and by feel.