Critical role has really taught me how to be a better dm, basically make up the rules as you go, make maps for literally everything, and lead with half truths, even if the player roles a 20 never give them 100% of what they want, make them want to look throughout the map you created for them, give out minor hints, and details about what they see, make then afraid to explore, but also curious, and frustrated about what they want to do, and finally reward teamwork. Especially if you really see the player trying their hardest to succeed