What do you wish you knew when you started?

I haven't ever invested in anything, I know nothing about stocks, the stock market, investing, or anything of the sorts, let alone how to invest in ethereum. I've watched countless youtube videos, had friends try to explain, read articles, and in the end, it just doesn't stick and I'm as confused as ever. I've decided to just go for it and invest what I'm willing to lose. I was hoping to hear what mistakes or choices you made that you wish you didn't. Or at least things you think are really important to your success. Thanks in advance!