Please share here and also add a short comment why it is your most important crypto advice.
My most important crypto advice is "not your keys - not your coins" because it is simply a very important advice, where we should be aware to have real access to our coins and don't need to rely on a middleman. Bitcoin is clearly designed as a P2P currency.
I recommend you read the book "The Bitcoin Standard" by economist Saifedean Ammous, as well as the book "Broken Money" by author Lyn Alden.
Curiously, a few days ago the user Pmalek posted that S. Ammous gave his permission to download his popular books for free from a link he retweeted, so those who want to learn about "The Bitcoin Standard" but don't have much money to purchase it can get free knowledge, which is a great move by the author IMO.
Link to the thread where this is discussed: The Bitcoin Standard and other S. Ammous books for free!