When I get ready to go to the grocery store, I rewrite my list so that the items are in order from the left of the store around to the right. If I don't have to go back and forth across the store I save time and make fewer impulse buys.
I work night shift, so I track my breakfast (which I eat shortly after midnight) lunch (about 5 am), afternoon coffee and snack (9 am right before bed) between midnight and 3 am. So that way I know how many calories I have left for dinner. For those on a normal schedule, just track the night before!