But the simplest form of marketing is often to tell the right people that your product exists. I've found Boardgamegeek.com to be an invaluable resource for doing that, which is why I think every game designer who has an interest in marketing their game should check it out.
After getting back from Gen Con with How to Host a Dungeon, I got it listed on Board Game Geek.
I had a couple of reasons for this. One, I wanted to see if there was a market for HTHTAD among board gamers. Two, I wanted to see what would happen. In September, the month I was listed on BGG, it produced 538 hits on my Web site out of 1294 total, or 41% of my traffic.
I have no way of knowing how many of those people bought How to Host a Dungeon, but I sold 42 copies in that period, so the math suggests I sold 17 copies thanks to my Board Game Geek listing, WHICH IS PRETTY FREAKING AWESOME BUMP, in my humble opinion.
After September, the numbers drop. BGG gave me 65 hits out of 695 total, which is 15% of my traffic (and by the same math, 3 copies sold). Looking at my BGG page, I see that 11 people list themselves as owning How to Host a Dungeon. The real number is probably higher, possibly MUCH higher.
My person hunch is that possibly 1/3 of my post-Gen Con sales came from people who discovered the game through BGG, which strongly validates point 1: there is an audience for my game on BGG.
I hope that's helpful to someone who's marketing an indie board game. I'm going to post a bit more on this and talk about what I learned about BGG, and the mistakes I made using it to promote my game.
We're having a useful discussion on this over at Story Games right now as well.