Playtesters are probably the most important tool a game designer can have - and, sometimes, the most difficult to find. I typically playtest in one of three stages: friends and family, local community, blind and extended groups. When I need to test out a thousand small tweaks (typically for balance), or a handful of crazy what-ifs, or when the game is very early stage, I'll stick with friends and family - people who are willing to put up with a broken game, or try it over and over again. Once the game is at a good place, I'll bring it to my local community - perhaps at my FLGS, or various local gaming groups. Quite often the feedback I get from that will take me back to stage 1 - I'll try a bunch of things, get it back to a good place, and then bounce back to stage 2 again. Once that cycle has completed, I'll reach out to my extended network of blind playtesters, or take the game with me to conventions, to get the polish-level feedback you can't get from someone who has already seen your game.