"I am not a perfectionist", Siad Isac Asimov, author of 475 books. "I do not look back with regret and I do not care what I wrote." Be careful, but do not worry about your task, to the point where the additional effort no longer causes a proportionally interesting improvement in your final product.
Be excellent, but not perfect. Clients do not have the time or the budget to perfect; For most projects, it is sufficient to achieve 95 to 98% of the way to perfection. That does not mean you make mistakes on purpose or do less than you can. This means that you stop polishing and working with work when it suits you, and it does not bother you that you do not spend more than 100 times on it. Build it, check it and let it go.
Understand the exponential curve of excellence. Quality improves with effort in an exponential curve. This means that the first efforts will give the best results. Subsequent efforts lead to increasingly smaller improvements until the small performance is not worth it. Productive people stop at the point where the incremental incremental investment justifies investing in an extra effort for a task. Strive for 100% perfection and it is unlikely to be productive or profitable. By constantly pressing between 90 and 98%, you maximize customer satisfaction and the return of your time investment.
"Perfection does not exist," Alfred de Musset wrote. "To understand this is the triumph of human intelligence, it expects it to be the most dangerous form of madness.