Last fall, I began hitting the ball toward the heel a little bit. My swing felt fine, but I wanted solid contact and couldn't find a swing thought that worked at getting my swing back in the groove. A week or two into my "heel funk" I found my high school golf diary: a hodge-podge of notes, swing thoughts, diagrams of holes, and more. I flipped through and found a perfect swing thought (this tip isn't about that particular swing thought, so I won't share it here).
The lesson here is clear: keeping a diary can save your butt down the line. Your golf diary may include information like swing thoughts for the day, information obtained at a recent lesson, general trends (i.e. "hitting slight fade" or "hitting lots of shots thin"), or more. Some golfers might even keep track of their hats so they can identify which is their "luckiest."
Diaries aren't just for little girls, you know.