1. Don't read aloud the read aloud text. Paraphrase.
I personally completely tune out read aloud text when I'm a player.
2. If playing with DC's, say the DC aloud prior to the players roll. (except in the case of knowledge or perception based checks, because its far more entertaining to leave that unknown, as per suggestion by Zak.
3. If you have a player doing mapping show her/him the starting point.
4. Come up with at least three silly voices in your spare time for NPCs.
5. Look around the table. Is someone bored? Engage them.
6. Roll wandering monster checks.
7. Don't show the players a picture of a monster. Describe it.
8. Rule something, look it up later.
9. You are there to facilitate the descriptions of the world. You are not on the monsters side, or the players side. Do your best to remain impartial when you can.
10. Railroading is silly. However if something needs to "happen" and it doesn't, you can always arrange for it to happen at some other point. ie "The Quantum Ogre Theory".
11. How much prep you do is entirely up to you. Knowing the adventure you plan to run (inside and out can be helpful). At the very least having a few NPCs ready to go will save your bacon. NPCs don't always have the PCs interest at heart.
12. If your players think you are fudging, roll the dice in front of the screen.
13. Roll dice randomly behind the screen, look down, nod. Move on.
If you have more to add, go for it.