Making a game seem alive and 'real' is a challenge all gamemasters face, and NPCs can be the hardest element to get right. If the players ever decide to search a bag, briefcase, or box that an NPC was carrying, coming up with the contents off the top of your head can be a real chore.
120 Modern Bag Contents offers a quick list for the busy gamemaster to pull out as needed. Refer to the list and pick the items you think the NPC would have, or roll some dice and use the result(s) you get. A few of these items could be hooks to different adventures, or they could simply be red herrings. Several example entries:
11. Board Game
50: Holiday Photos (in an envelope)
90: Signed Poster
While the list is targeted at gamemasters running a modern or near-future game, it could work with some modification in a sci-fi game.