You could check on BGG to see if your state/city has a thread for local game sales, for example boardgamegeek.com/geeklist/293...

Board Game Geek, Geek Trades, /r/boardgameexchange, Facebook, Craigslist, Meetup, local game groups constantly have people selling and/or (more frequently than you'd think) giving games away which could also be you!

I've only sold three ways: Facebook Board Game Sell Groups, boardgamegeek.com, and specific live meetups (e.g., PAX Unplugged Flea Market, or local game group's annual 'Board Game Swap' (sale). Your ability to sell goes way up if you take a look at the resale market and price at least 10% below.