Don't over think. I have to tell myself this regularly. Over-thinking puts the rational brain in front of and in the way of the creative brain. If you overthink the design of a piece, it may never see the light of day. If you focus on making each part of the overall composition perfect, the full composition may never get done. If art for you is frequently an expression of emotion - if the self-expression is as important as the craft, then overthinking is your enemy.
This is distinct from craft and technique, though. There are pieces I make that are not "practice pieces" but are experiments in technique or for improving the actual"work" of quilting, so that I can create from instinct and emotion when I need to. Thought here helps - how can I make it so the craft does not impede the expression?