Learning to enjoy, or at least better accept, making mistakes. Mistakes, whether in carrying out a scientific experiment, writing an unclear sentence, or hitting the wrong note on a musical instrument, are utterly necessary early-stage behaviors. No one starts out doing something flawlessly. Mistakes contain more information than most successes, but people get upset about making mistakes, and give up useful training, so as not to go through that perceived "failure."
Within reason & particularly in the early days of anything, mistakes should be welcomed and appreciated as authentic learning. If not, they are more likely to be repeated.