Tip 1: Always buy games as gifts! After Steam Sale, you will suddenly find ten new games in your library, and half of them may never be played. If you have bought the game as a gift, you can still forward it to friends (or install it yourself if you have time to do it).
Tip 2: There is a wishlist on Steam: Use this list to track your favorite games. After the game is discounted, you will receive an email.
Tip 4: If you have made a bad purchase, don't be afraid to panic: You can return any game purchased on Steam within 14 days with a maximum playing time of 2 hours without giving any reason.