I'm sitting down and preparing for my groups first session (and my first session ever as a GM), and I was just wondering; How do you all prepare for a typical session?

I'm down for plenty of improv when it comes to gameplay, but at the same time I don't want to get caught in a situation where I'm making things up and it's very obvious. So how much preparing is too much?

I generally start with a couple of encounters as set pieces (setting, scene, NPCs) and flesh them out how I'd like them to look. Then I cook up a way for them to get to said set piece.

For example, they are contacted by Booster Terrik for a possible job (the offer is a spice pickup from a storage canister on Corulag, a large order that needs to happen ASAP and as covertly as possible, due to the storage facility being reclaimed for government usage). The setting is Gus Treta Inner-System Market Station, and while they are chatting away with Booster the cantina that they're in is the target of a hold-up: a local gang comes in, since they have a bone to pick with the owner of the establishment. And while they're at it, they demand all the patrons of the place hand over all their valuables.

If the players don't contact Booster Terrik aboard the Gus Treta, but instead rush off to Ando Prime, perhaps they are approached by a different sentient with the same offer that Booster Terrik would have made them. During their negotiation, the encounter above with the local gang would take place, either in a cantina the players find themselves in or even in the open marketplace surrounding the local spaceport, and the heroes are simply in the wrong place at the wrong time as they find themselves the targets of a mugging.

During the first session, it's often also a good idea to establish something that the PCs really want, and are willing to chase after (the MacGuffin). This works best in conjunction with a character's obligation, and if found this MacGuffin could significantly reduce the obligation of one or more PCs.

I have been running adventures for the better part of 3 decades as a GM and their is one universal truth about a typical adventure, players WILL deviate from what you have planned and you won't be able to stop them without it being obvious that your doing it.

As such the most important aspect of preparation is really knowing the adventure, knowing the motivations of the NPC's, having a strong sense of the setting and having a strong vision of the universe. In essence no matter what the PC's do, you should know exactly what a place, NPC or situation would look like in that universe and be able to create it on the fly. Aka, the players decide, lets go to a cantina, you need to know what a Star Wars Cantina looks like without having diagrams or written out scenes or stats for for it.

Another words, whatever the players do, wherever they go, it should appear as if you knew they where going to do that and its part of the adventure.

Its why I always say first time GM's should run games in settings they are intimately familiar with so that its very easy and natural for them to describe surroundings and come up with events, characters etc.. on the fly. I think in part this is why Star Wars is so popular as a role-playing setting, most of us have seen all the movies, read books etc... even without picking up the Edge of Empire book most people are already familiar enough with it to know what things would look like.

Stats and things.. they are important and shouldn't be neglected, but again a good roleplaying book will have that stuff in their and Edge of The Empire has done a great job on that end. Knowing the rules is vital as well, you should be the expert in the room so read the book cover to cover.. its your bible as a GM.

My personal take on preparation of a first session is a focus on character creation. You really want to make sure the back stories, motivations, goals and just the general start of the adventure is unified among the various characters/players. Another words, people shouldn't be creating characters at home and then turning them into the GM for approval. Character creation should always be done together, backgrounds should be defined together and as a GM you need to really guide players to create a real "team" that's diverse in ability but united in motivations and goals. Now this isn't true about every roleplaying setting, I wouldn't for example do that in a world of darkness game, but in a game where players share a starship, their enterprise must be very unified or else it will be a problem.

In terms of Edge of The Empire specifically I would also say, really slow it down when narrating. Its not so much preparation as a style of running but you want to make sure in this game that each role is narrated, each action vivid and each scene really illustrated in the minds of the players. If you don't do that, instead of Star Wars your world will appear to be a generic science-fiction game. Its a vital element of running a Star Wars setting. You want to really drive home the little details and that can and will slow your game a bit, but I think you'll find your players will appreciate it. In particular focus on creating narrative results to die rolls. The systems genius is in those specialty dice and when used right its truly a remarkable gaming experience.