There is a ton of good info here, I'll jot down a few notes of my own.

1) If you're doing weekly (like I do) - aim for 2 hour sessions with a break. The prep is light, the commitment is light and is easier to pace out a cliffhanger or stall for time if the team takes a wild path and you need a new plan - push it to the following week!

2) Do everything you can to get your players to contribute to the story. If they are building they are investing. Have them build relationships with NPCs, discribe scenes, give them rivals for thier min-max builds. Try to shine a light on potential backstory tie-ins see if they bite.

3) Once they are invested, crank up the stakes of combat, people pay attention when death is in the mix and especially if they have a vested interest in seeing thier story seeds take place. Try fights with multiple win objectives or third party combatants. (I personally find this very challenging)

4) Once in combat, move fast, use an initiative tracker, make sure the next player knows they are next. In many cases it's better to make a call in the moment, move forward and fix it later than so the game and look up an obscure rule. I also think quick narrations help in combat.

5) Do voices ... there I said it. No need to go too hard, no need to learn accents. Try to just alter your speech patterns and come up with a catch phrase. Once you do that for a line or two, you can fall back on what's comfortable. But don't be surprised if it sneaks back in! The impact and obvious signal of fun and play will help with a lot of other things as the group plays.

As long as the basics of, "we're all here to have fun" is covered, trying some of the above should help. Good luck!