Well, be proud of what you built. You don't have to shamelessly self-promote constantly, but don't be afraid to let people know about your app. Try to promote it where and when it makes sense, but only in a reasonable context.

Think of it this way, you would expect an Apple employee to talk up their latest iGadget if you asked them about it, and they certainly do advertise a lot, but you don't see them doing a bunch of blog comment spam to push traffic. Read some Yahoo news article comments, usually the first 5-10 are dating website comment spam. Stay away from that kind of thing and you're probably fine.