Do you mean bad reads or bad calls or just plain errors like misreading the board? If you mean bad reads meh it happens. I can usually justify my bad calls as trying to send a message or just curiosity or being outplayed. I saw the best player in the world muck a winning hand because he misread it. It's hard to stay focused for hours at a time. IU get over it by not letting it bother me in the 1st place. Good luck.
Its hard to pick a number. As few as possible? Lol I have learned that you dont need to go all in to be super agresive, that way you still havena chance if you lose
I keep making error in online tourneys that when I know a players drawing if I bet enough to make it incorrect he will fold his draw. Not the case lol.
If you make plenty of errors, maybe take a break from the game. You could be tireder than usual, maybe make sure going to the gym to keep yourself fresh for these tourneys where your sitting still for long periods of time
We all make terribly errors and want to crawl up in a ball.. But we move on
If I define "error" to include any sub-optimal play or judgment, I make lots. At low stakes, it's more about making fewer and/or less costly ones than your opponents, not about playing anywhere near perfectly.