New here, learning from sizing mistakes early on

Hey everyone, just joined Traderforum. Been dabbling for a bit, mostly focused on crypto until recently, now looking at forex as well. A big lesson I learned early on, and one I'm still actively working on, is position sizing. I've blown up a couple of small accounts trying to 'make it big' too quickly, essentially risking way too much of my capital on single $BTC or $ETH trades. It's hard when you see those quick pumps and want to maximize gains, but I'm realizing now that proper risk management, especially sizing, is the absolute bedrock. Looking forward to learning from all of you who have been around longer. What's one foundational mistake you wish you'd avoided earlier?