Be positive. Lots of people are negative. They will be drawn to you... wait, well it's better than being repelled by you!
Give each one a complement once a week, on a different day. Don't make it about their appearance specifically, or they might start to think you are attracted to them. Say something such as "you're looking well?" act curious.
Even if they feel horrible, this will boost their ego. It's okay if you skip a complement here and there, better to give less than go overboard. And try not to give complements when others are around - jealously is rife among the Normals.
Sometimes they won't be well, if they start to offload their bad mood experience, try to listen for a bit, and empathise "yeah that sux". But NEVER offer advice, for some reason they want to attack good advice givers & truth speakers. Just listen and say "oh, no", "yeah?", "damn!" Excuse your self after a bit "I've got to get this task done now." You can offer to listen to more of his story at lunch (if you can handle that).