If you are
GM'ing I'd say start small, start simple, and don't try to use every idea you have right away. In fact, I'd say that if you have a great idea for a campaign
don't do it at all until you and your group are familiar with the rules.
What I suggest to a
GM is to read the rulebook and then read the rulebook again. You don't necessarily need to read all the background fluff, but you will need to know the sections on how the game is played, how combat works and so on. Having a working knowledge of how Skills and Talents work as well is also a must. As the
GM you don't have to know character creation backwards, but it helps if you're taking your players through it step by step. I'd suggest ignoring the whole Psychic system to start with (so don't let anyone play a Librarian) and ignore Squad/Solo Modes until your group has a grasp of the basic rules.
You can even start with the basic adventure that's in the main rulebook. Read it over, get a good idea of how it is run and how you'd like to run it, and if you're not doing pre-
gen characters for your players (which can speed things up and gets them learning the
game rather than just character creation) you can ease them through the first few encounters and plot points as they get used to each part of the game.
There's also the
intro adventure they wrote for Free
RPG Day a year or so ago (and it's
sequel). They could also be good places to start (and they also have
additional characters and
an FAQ).