This has been said before, but worth the reminder when you find yourself fiddling with a sentence for half an hour, trying to get the rhythm just right, even though you don’t yet know what the hell it is you’re trying to say:

Your day’s work might turn out to have been a mess. So what? Vonnegut said “When I write, I feel like an armless, legless man with a crayon in his mouth.” So go ahead and make big scratches and mistakes. Use up lots of paper. Perfectionism is a mean, frozen form of idealism, while messes are the artist’s true friend. What people somehow (inadvertently, I’m sure) forgot to mention when we were children was that we need to make messes in order to find out who we are and why we are here—and, by extension, what we’re supposed to be writing.

Lamott, Bird by Bird, page 32

You could replace “writing” with “designing” and this would be just as true.