The use of checklists has become a cornerstone of my GTD system. I have two checklists -- one for home, and one for lab. They're each broken down into key time periods, such as early morning, arrival at work, departure from work, arrival home, and bedtime. Here's the really neat thing about checklists: they're a habit shortcut. All you have to do is establish the habit of going through your checklist, and you can automatically pick up a habit of doing anything you put on your checklists. They have a secondary benefit, in that it's easier to tweak your routine in checklist format. If you notice that things should go in a certain order, you can put them in that order on the checklist. If you find that the existing order isn't working for you, then you can rearrange it. Typically I print them for a week at a time (made using spreadsheet software), so I update the file and then the next week it takes effect. Here's an example of an ordering issue I tweaked: I keep my Next Actions and calendar on my Palm Treo, and every morning when I get to work, I sync it with my computer to pick up any changes I've made since I last left work. This sync takes a little bit of time. I found myself sitting and waiting for the sync before I could continue down the checklist, so I moved the sync to the beginning, and placed other things I could do while it was working immediately after it. Poof, I got back 4 minutes every morning. You can get a copy of my lab checklist to see what I'm talking about here (PDF). Do you use checklists?