I've found that if I write something down that I am dreading doing, and make an appointment with myself to get a start on it at some specified time, I am MUCH more likely to actually do it and not procrastinate. It's not 100 % but it's more than the 35% I achieve when I don't do this.
So for instance, I have been bothered for a couple of weeks every time I stepped into the garage because it really does look horrible. I cleaned it last summer, but not since.
1. Commit to a start. So since it is a BIG job, I commited myself to spending 10 minutes a day on it. I think Flylady calls this Taming the Dragon. Anyway, that's how I think of it. I can almost visualize myself picking up my gauntlets, sword and shield and going out to spar.
2. Let it percolate. Giving myself a time in the (near) future allows me to figure out the "first step". I usually pick something easy that will pay off heavily in terms of how the place looks. So for the garage, the big "easy" thing was the bicycles all over the place.
3. Set a Date. I made the appointment for today, and when I had a few extra moments this morning I decided to go ahead and get the battle over with. Of course, once you start it's usually not difficult to do a bit more than the minimum.
4. Don't Overdo It. I try hard not to get carried away at first, with a big job. You can burn out that way and short-circuit future efforts, giving yourself an aversion that lingers. (this conscious reining-in may not be necessary for everyone, but it is helpful for closet perfectionists)
5. Plan while you work. Once I had engaged with the work, I naturally came up with the next step, and the next. It's useful to stop with a next step already in place (I found this out as a writer). That way, it's easier to pick up the work at the next session.
6. Delegate what you can. I actually left the bicycles for the boys to put away in the basement, and spent my time picking up and straightening.
7. Keep going. Now, I will try to spend 10 minutes, at least 4-5 times a week, working on this. I usually find that at some point there's a small enough bit left to do that I can spend 30-60 minutes and just FINISH. The trick is to wait for the right time to use that finishing-up momentum.
8. Be OK with 85%. I have learned to tell myself "good done is better than best undone" or "don't make the best the enemy of the good". If I can make it to 86% or even 90%, that's nice, but I try save the 110% effort for things that are of primary importance -- nurturing a sick child, or my prayer life -- things that are going to make a difference for more than the next week or month or year.
So there's my Dragon-Battling Checklist.