What mistakes should I watch out for as a crypto newbie?

I am just getting into crypto, and imo some of this stuff has a lot of potential. But I've also seen countless people lose thousands of dollars, and it's a fate I would like to avoid. What dumbfuckery did you commit when you joined this community? Is taking some Ls unavoidable? When is it a good idea to invest in altcoins, or should I just stick to BTC and ETH for now? Can you recommend some interesting projects with real life applications that are still receiving updates? What are the most common scams?