Interesting question and I would come back to see what others write.

For me, my first recommendation would still have to be BTC as that is the "most stable" or "safest" crypto out there, and likely the first crypto that institutions will likely adopt.

As for the most important info, I think it's important to understand the security aspect of cryptos first. For example, what are hot wallets and cold wallets, identifying which exchanges are more reputable to open accounts with (cos you don't want an exchange that is a scam or disappears overnight), knowing what seed phrases and keys are and how to keep them safe (i.e. never to share or post anywhere).