This is a very hard question to answer. I think, talk about our games and our love for them in public. I know I've had people express interest as a result of that - usually people with a background in either writing or acting or both, so maybe we should start targeting these groups?
The next step is to actually get a game together the interested new people can join, which is where I always fall down.
Finally, when someone new does join your game, make sure they feel welcome and included. Lead by example at the table, demonstrating the way your group tends to play, but make sure they have time and space to take part and don't end up an observer to your glory. Help them out a bit if they get stuck, but (here's the trick!) without being patronising. Ask their opinion after, ideally without that starry-eyed wonder that I know tends to take me over when I get to talk about my games. Ask what their character did that they enjoyed doing; ask what they'd like to explore next time.
If you're taking part this year, please leave a link to your response below.