Nilhgualcm Leahcim said:
What do you, oh seasoned ENworlders, do to prep a premade game? Please help.
First I'd read the adventure again, then once that's done, read it again, followed by reading it again. Really the key is getting to know the adventure, where it's going at any given time, what places player's may go off the beaten (or written) path and how to get them back onto the right one, etc. You don't have to memorize every boxed paragraph, per se, but having a good understanding of the overall goals of the adventure and key points in the plot is extremely helpful.
I also like to go thorugh each encounter and jot notes down on either Index Cards or some paper, things like hp for various monsters (to keep a tally on scrap rather than in the book), special things to look out for, areas where I want to elaborate details, places to insert music (I put key parts of the module to music, this only works for some groups). By prepping modifiable things on paper ahead of time, it beats the mad scramble to dig up Intiative modifiers, AC, and hit points of creatures during tense combat on the fly, as well as making sure you noted important parts of the encounter so you don't pass over them during the session.
As stated before, there's actually more prep in a premade than something homebrew, you can modify homebrew on the fly and not worry about screwing up something that appears later since it's your world, premades don't always give you that luxury.
Oh, the other biggest thing to prep for, know that your players will not follow the adventure to the T and any point where they can go the wrong way, they will. It's part of the Collective Player's Associates (CPA) rule on frustrating DMs, you'll get used to it though
~Me