A lot of pretty classic but good advise, There is already a discussion on PvP, but here are two cool ones

Don’t overprepare. I have an inexpensive egg timer. My partner hates its ticking sound. So I use a watch instead. 30 minutes for a session. That’s how much I give myself.

That one is the biggest killer, beginner GM carefully think about tonight tavern, the innkeeper has a name and a description, the bard is going to tell a story about missing kids, there is even a menu for the night. Except that the PC are like There something weird in that town, May-be their food in poisonous we shouldn’t stay too long in the tavern, you’re right let’s camp in the wood and keep watch Tons of stuff prepared by the GM end-up in the garbage (Or for another session). So keep an outline, and as the author said, everything is a bonus.

Keep the game running and review rules after.

Looks like one of the most basic advice. May-be you forgot about how black-smithing works (To take the kind of rules you won’t use any time). But at the end, just find an appropriate skill/mechanics and problem is solved. May-be you missed a point and were too nice/harsh, but at least you didn’t spend 15 minutes re-reading a rules.

Be consistent and predictable.

This is IMO the best way to fix 90% of game planning problem, session occurs at a fixed date, not matter who’s there. Worst case, you do a board game, or have a drink. but if you wait for everyone to be available, you won’t play much