It's hard to say without knowing what interests YOU. There is nothing as attractive as passion. Think about things you are passionate about and bring that to your room. Think about what's fun to you. Other people with similar interests will find you.
You'll have more success talking about things that are also of interest to you, and if you have fun, your members will have fun. If you have a look at some of the random chatter here, you'll see that pets, video games, movies and TV shows, professional sports and food are topics people are interested in, and that you can have fun with. Art's interesting, but good luck getting members who care. Music can be good, if you are into it. I trade music with one of my model friends. Ask if they have hobbies. Do you have hobbies?
Politics and religion are obviously stuff to stay away from. If anyone brings it up, change the subject FAST. That's just poison, and generally unsexy and unfun.
People want to get to know YOU. Think about what is of interest to you, and that you can have fun with regularly. If you don't go out to movies, watch the new ones online, either the whole thing or trailers. If you don't like sports, read the stupid gossip about athletes and their love lives. Got a pet? They're fun, and people like them, no matter what it is. I was in one session in Heidi_Voltage's room where everything revolved around a suckerfish and it was a hoot.
Good luck.
