If you’re a painter or calligrapher, say, this is an easy one to practice. If you’re a musician or dancer, it’s harder. But there are ways to keep looking at your stuff, even if it’s a song or a performance.
You’re not doing this to leave a work in place forever. You’re doing a little study. It’s a personal gallery visit, and the assignment is to analyze this one work. It just happens to be yours, this time.
What you’re looking for is anything that keeps the work from being perfect and anything that helps it along the way. That’s a little hyperbolic–nothing is perfect—but perfection should be striven for, not achieved. And it’s nebulous: the main thing is how closely it came to the vision in your head. But you need some perspective, a little objectivity, a little time for it to breathe and live before you can see the little things.
You already probably see the mistakes you made and other choices you thought about but didn’t implement. Next time you’ll know they could have helped improve it, and some things to keep that went well.
This approach works better if you have just a little difficulty or a slight embarrassment when examining your own work than if you either want to puke from thinking it’s terrible or you think it’s brilliant, but I think those cases are rare.
More often, the art you made took a long time and you’ve spent hours, days, or weeks getting it honed, chopping it into shape. You know it well. You also can overlook the obvious.
So as you make more things, keep a fresh one handy to listen to or look at to see it as plainly as you can, to learn one more lesson from a finished thing.