Nothing is more important in your game than a consistent putting stroke technique. Trust me, practice truly makes perfect when it comes to putting. You can be the best player from tee to green but without a good stroke on the greens, you still won’t be able to put up the score you want.
It is important that you pay attention to both the speed of your stroke and the length of your stroke. Both back and through. Some golfers like a short, quick putting stroke while others prefer a longer, smoother stroke, as I do. We want the putter head to travel the same distance on the through stroke as it does on the way back. Using a metronome (in an app on your phone) can help you practice this skill. Following a steady rhythm as you practice will create consistency in your stroke length. The speed of the putter head should remain constant or slightly increase on the way through.
Master your putting stroke technique and your game will be far more consistent from any length of the putting green. Wearing a sleeve that reduces extraneous movement while practicing can certainly help, but what matters most is that you practice.