How do you promote your work?

Because type design is only a part-time hobby for me, I never focused on marketing my work, and I sell solely through major vendors. I make some nice supplemental monthly income from regular desktop licensing there, but I know nothing about my customers. One of my typefaces consistently outsells my others, and I don't even know why or how people found out about it (google search reveals barely anyone mentioning the font). Basically my web presence sucks and I'm not sure who my customers are, so I'm unsure on how to find them let alone promote to them. 

What are the strongest channels font marketing? Is it connections with agencies and purchasers? Type blogs? Is social media a big part of it?