1. Matthew Colville
Matt Colville run's a YouTube series on how to be a DM with all sorts of great advice how to run the game.
2. GM Tips
Matt Mercers tips on how to be a DM.
3. DM's Guild
The DM's Guild has a load of good content for adventures and campaigns.
Ascendant campaigns can view previous versions of their pages, see what has changed (and who did it), and even restore old versions. It's like having a rewind button for your campaign.
We've already been saving your edits, so if you
you will have instant access to your previous versions. Plus, you get a 15-day free trial, so there's nothing to lose.