Over the long haul, I'd suggest two things:

1) Participate normally. Ask good questions if you have them. Give good answers when you can. Try and keep the stack nice and clean and helpful other ways in the meanwhile.

2) When its appropriate to do so elsewhere, make sure to link back here and/or promote this stack. I don't go around pumping for History.SE on my twitter feed or /. account, but if something comes up that's answered here (or could be well-answered here), you can bet I'll make sure to let that be known.

The one really positive trend I see is our traffic seems to be ever increasing. I have to think that at some point that will start translating organically into more posts.