One of the more key things for me (and mentioned by BN up there too) is
p a c i n g
And in particular, understanding that certain things take more time than other things. Asking PCs to brainstorm their own solutions, asking PCs to choose between a variety of options that may have good or poor outcomes, puzzle solving, talking to NPCs, resolving in-group disagreements as to approach, these all take way more RL time to accomplish than you’d sometimes think.
It’s important to keep it moving, it’s important not to get the players stuck on decision points or hurdles that won’t ultimately matter. Understanding for yourself how much time combat in your system generally takes (and how to keep it flowing relatively quickly) is important. And knowing which things are slow is important. It doesn’t mean you can’t do them, but if the PCs need to talk extensively with multiple NPCs and then have a fight, those may need to be separate sessions.
Back in the day I think events could be very long chunks of time and now you’re probably lucky to get 2-3 hours, because everyone including the GM is busy and has kids and has work in the morning. Pacing is key to get the most out of limited time chunks available.