I found that the easiest way for me to mess up isn't misreading the direction, but losing control of my position size: when spot prices go up, I want to take more; when there's a pullback, I get scared and want to sell; futures are even worse, thinking "just a little," accidentally adding until my heartbeat speeds up, and in the end, it's not a stop loss but a forced liquidation. To put it simply: don't let any single trade have the power to break your account curve.

Now I've set a rule for myself: lose no more than what I can calmly go wash a bowl over, even if it's just 50 bucks to test the waters, wait patiently, no rush.
Recently, I saw someone complain about on-chain tags/data tools being laggy and possibly being manipulated... I don't really trust these anymore; they can be referenced, but for position size and stop loss, don't rely on tools to take responsibility.
That's it for now, losing a little less is okay, just don't die.