Here's the problem with perfectionists: They see the world as a 2 dimensional chart, with the "level of perfection" running along the X axis, and the "effort" running along the Y axis, like the diagram to the right.
But what the perfectionist fails to see is that there is a third axis - time. Time is our most precious resource. We are all given a short time to do our thing on this planet, and being a perfectionist cheats you of the ability to work on all the things that have to get done.
What the chart *really* looks like is more like the second image, at right, with the Z axis representing time. And by definition, being a perfectionist means you are using up a lot of your time... how ironic that the perfectionist is very much an imperfect user of time, the most precious resource any of us have.
So instead of trying to make something "perfect", just make it good enough to get the job done, and spend the time you would've spent perfecting it on something else. (See my related post on the 80/20 rule.)
And by "good enough" I don't mean substandard or sub par. I think most of us know when we're being perfectionists... it's kind of like the Supreme Court's definition of pornography.... it's hard to describe, but you know it when you see it. Especially if you have a history of being a perfectionist, you'll know when you are overdoing something. So just make yourself stop and use that time to focus on something else that needs to get done.