Mistakes and unsuccessful works

Mistakes and unsuccessful works is something that happen in life of every artist. Sometimes it is expected (when you try something new) and sometimes it's just a bad day, even if you do a familiar work.
At first, I really worried about it. I was redoing, getting upset, redoing again and again until I get completely exhausted. I could return to this work only after a few days or even weeks, because I was sick of it.
How did I handle this?

I had to wash off all the work that I've done

Experience - when it happened the first time, it's very frustrating, when the 10th - you just start to get used to it.

Have a procedure, which will lead to a result. It's really calming. The most nervous moment for me is the very beginning - the distribution of tones. Very experienced artists can start from a small piece, render it completely and move on. I'm not at that level yet, so firstly I build value relationships.
For example, it's very hard to judge how dark the color of the skin is, if you didn't fill the background. Once I go for a skin colors (and almost fully rendered it) and forgot to fill the background. It turned out that what looked good with a white background (pale skin), with a dark background looked washy, so I had to repaint the portrait.
When I picked up the tone/color I know that the further work will go well, and the fear that the result will disappoint me disappear.

Value/color sketches - how many hours and nerves I could save, if I was always doing preliminary work! Even if you want to try something new (fresh idea came to your mind), add a little pop of color, try not to do it on a big canvas - do a quick sketch, because the risk of spoiling everything is pretty high.

Value sketch with a painting

Anyway, mistakes are inevitable. If you feel that the work is bad don't get stuck, don't blame yourself, do not dig deep, take you time - stop the work, have a cup of tea and go play video games. Then getting back to work will be so much easier.  And sometimes you just need to throw that unsuccessful artwork (or hide it, so you won't see your failure).

Wish you a lot of success at managing your failures!