People made this mistake in 2021, and I'm seeing it again:

Investing in dozens of assets without a solid thesis to back them up.

Every decision must be backed by fundamental, technical, and/or on-chain analysis. Then, it may or may not be fulfilled.

Don't have more assets than you can control. I rarely have more than 25 assets in my portfolio, and I'm a full-time investor and have been doing this for a long time.

If you haven't learned how to analyze well yet, get trained, either by paying or investing more time for free.

It will be cheap, because otherwise, you will most likely end up with dozens of diluted altcoins at the end of the cycle and with almost all of your money lost.