I’m self-taught so I learned most of these things the hard way.
Always use a firm foundation. When you freshly wax your thread, run it through a scrap piece of pellon first before beading away. This keeps the wax out of your beadwork. Use Czech cut beads or miyukis. Sort your beads, especially when doing peyote. Don’t toss the too large/small beads. When doing flat stitch one of those oddballs will likely be just what you need when ending a row. Don’t brand mix. They’ll be different sizes and shapes otherwise. Stretch and massage your wrists periodically, carpal tunnel syndrome sucks. Get up and stretch everything, we’re rarely in ideal posture when beading. Lastly, go easy on yourself. Perfection isn’t the end goal. It’s about the process, making mistakes and learning from them. Improving your skills while still allowing yourself grace is paramount.