Not a problem I often fall into. (If you know me, please feel free to snicker.) But it can be a real problem for artists or designers. Perfectionism can cripple. While you, the artist, need to do the best work you can, you must resign yourself to inevitable flaws.
Isn't aiming for perfect a good thing?
High standards and dissatisfaction drive better work. But focusing on "perfect" backfires: either you never finish (the work never got perfect, what a surprise!); or you focus tight on one tiny aspect that you can perfect, letting the rest wait; or you never begin, knowing how far from ideal any result will be. Perfectionists, oddly, tend to be underachievers, because they won't risk doing what they aren't sure of doing well, easily.
No, the interesting work gets done by those willing to mess up. It's the What-the-Hell! folks who make breakthroughs. It's the Wing-It!-ers who make messy mistakes and big triumphs. Imperfect-designers do try to tidy up their mess later, to make a good presentation to the world, but that's camouflage and public relations. I suspect you can learn to enjoy the breezy feeling of hanging over space with no net, just goofing, trying things, experimenting...
Perfection? Get over it! Perfection is boring.
What brought on this rant? I've been rereading favorite books on writing - Stephen King's On Writing and Anne Lamott's Bird by Bird. She has a great riff on perfectionism.