Do you daydream about playing golf while you are awake? When that happens, your brain connects the images in your head and the muscles that control those movements, and you complete mental reps. However, the most effective visualization techniques include as many senses as possible. To make the most of your mental reps you should see it, feel it, and hear it.
Using three senses makes the visualization more realistic and memorable and thus allows you to have an entire movie in your head.
The best time to visualize is right before bed, as your mind tends to replay those images at night. Play all eighteen holes in your head when you lie down to sleep. Use all your senses. See yourself hitting good shots and reacting to and recovering from bad shots. Take your time and dedicate twenty minutes to this process. Increase your mental reps!