At the very beginning of a new project, keep your standards low.
High-quality work rarely comes from building up thin layers of perfection. Instead, it’s the result of hacking together a half-finished, half-decent deliverable and tweaking it until it runs, then polishing it until it gleams.
Think of the fiction writer starting a new book. If she holds every freshly-typed sentence to the standards she’ll expect of her final draft, she’ll never finish the first chapter. But if she can temporarily lower her standards and get a few thousand words on the page, she has something to work with. She can add, cut, and rewrite. She can turn half-decent into great. But first, she has to create enough half-decent to have something to work with.
High standards at the end. Low standards at the beginning.