One thing I wish I had learned early on would be to approach every piece I do slowly, at least when it comes to self-study. Maybe I was taught that when I first started, but I don’t recall.
You’d be surprised at how challenging it can be to play something slow and accurate. Try working on a piece slowly, with no sustain pedal. It will sound weird, but there will be nowhere to hide and all of your flaws will be discovered.
Muscles do have memory and the more accurately you play now while learning, the quicker you’ll excel. It is much more challenging to go back and unlearn everything you did incorrectly because patience wasn’t applied from the beginning. I still go through that on pieces I started years ago.