In preparation for the murder mystery:
I started making potential victims! Ava Hofmann and her boytoy Lucas Taylor.
I've left their bios very unfinished because I want everyone to help make them. Since your characters may or may not be the one's killing them you should be able to help make them, so it'll be easier to make relationships and find motives. Even if you don't plan on participating in the murder mystery, you can still involve yourself by helping make the victims.
So start thinking on motives and who you might like to be a potential murderer (and I'm thinking too, maybe your character would hire someone to kill one or both of them, not necessarily pull the trigger themselves; we've got plenty of assassins for that purpose).
I'll make a post to start all this stuff up once our potential victims are a little more fleshed out.