That helps a good bit. I'll look into it, because when I last tried DM'ing something similar to homebrew Shadowrun, it was just way too overwhelming to go into unprepared.
While its good to be prepared, having too much planned can also be as frustrating, Not everything goes to story when you pre-plan, so the main things I have planned when running the game is..
Map
NPC's
Town / Community Status
The amount of things that can mess up a story line is tremendous but sometimes its for the best and thats when using your imagination and the "what would this character" do mentality comes into play.
I have a few stories I'm writing up that I'll post here about previous campaigns I either played in or ran. You'll be introduced to my favorite character ever the infamous..
Pentaro!, which turned into Pentaro 1 - 4, who eventually became Pentium after like half a dozen deaths.
Whilst the guy playing messed up with the plan, the way his characters died seriously can't be made up, some of the funnest times in my playing career came from watching awesome heroic gestures go into fumbling deaths.