What marketing tools/methods do you use for your startup?

Hey guys! My partner and I are just about done with our prototype. I've been reading, talking to various friends and mentors, and reaching out.

What marketing methods do you use for your projects? What has worked well? What hasn't worked so well?

As a freelance SEO trying to break free from "the ties that bind", my focus is marketing. Now I'm trying to bring marketing into the discussions on this site.