It's really up to individuals to keep an RP alive. Theres so few of us, Macro strategies really won't do us much good. On the individual player, I think overall there needs to be more pro-activity and less pure solo-posting. The more involved a player is, and the more people they are involved with, the more I'd say there is a need to stick around, but that is something a player. There's definitely a fear of people leaving though, and that is pretty much unfixable, there are a few members that come and go like autumn leaves.
For GMs, the biggest thing they can do is stick around. A GM that disappears is an RP that dies (Dust was revived by the great Foxrally, so it isn't a complete death sentence, but I'd ray revivals are exceedingly rare). A GM that encourages their players, and the stories involved with their characters will also go a long way. I think some of us, and I am guilty of this, put more emphasis on our story over our peers, and that is wrong. A GM, even in a story RP, should really focus more on guiding than directing, that way players can get excited on what they can do next, while not worrying about how many surprises a GM will have.
Also, posting more is huge. Can't force people to post every day or every week, but two or three weeks between posts always makes me anxious.
I'll probably remember this place forever