Congratulations! You are about to embark on an incredible adventure in the world of Zeitgeist!
Zeitgeist is a largely story driven campaign with lots of intrigue and roleplaying. Due to this, I have two recommendations:
1.) Zeitgeist has a diverse set of PCs. The text does a very good job explaining the backstory of the important characters and their motives. That being said, I found it very difficult to remember ALL the details. So I made myself a cheat sheet that contained the vital information. For a given PC that I believed was going to appear in a session, I wrote down their motives and fears. What drives them? What are their goals? What do they have to lose? What are they afraid of? What do they hate?
This made it much easier to roleplay these characters on the spot. If the characters got to a touchy subject, I knew they would not give up the information easily. Or if you pressured them in the right way, they would cave. If you want to go above and beyond, maybe write down a few lines of how you think they would speak or deliver a piece of information. I am not very good at getting into character on the spot, but this helped me a lot (of course I am nowhere near as good as the writing in the actual text...)
2.) Zeitgeist, in a way, is an amazing machine that runs itself. Everything, and I mean everything, has a reason. Every encounter/battle/interrogation has a reason for being there. So it is always important to understand the goal of each encounter.
This isn't your normal dungeon crawl where you open a door and an ooze stands before you. Why is that ooze there? Who knows! Who cares! Kill it!
In Zeitgeist, every encounter is a way to move the plot forward. A way to tell a bit of information about the world. If you can identify and convey this information to your players, every encounter will have much more brevity than your typical dungeon crawler.
So again, I made myself a list:
(For example)
Why are you fighting these dockers at the launch of R.N.S Coaltongue?
What information do I want to convey/give? (e.g. tension between the elite and the working class perhaps?)
With that, I wish you good luck! Zeitgeist is an amazing, complex, and daunting tale to tell. But very, very worth the effort put in.