For me personally I prefer to play shows that pay a set amount. Having to worry about pre-selling tickets, or a head count can be a pain in the ass. The band I am in will play shows for free, but only if the venue will generate a decent amount of new exposure for our band. Hence, being a coattail rider for an evening. Last, ideally while I love the stage, audience satisfaction of the music really drives me to preform better and put my all into the show. Playing a venue with bands of the same genre, or sub-genre really helps. If you're metalcore, try finding some other metalcore bands to play with, if the music is post-punk, then look for other bands in that scene to play with. Yeah I like the music that I play, but I want other people to enjoy it too. What I don't want is a bunch of people just standing there cringing, waiting for the next act, that happens to play music that is a polar opposite of the music that I play. However, depending on what your goals of the band are, a gig might just be a gig. If a gig is just a gig to you, then play every show you can. Otherwise, it does not hurt to be a little picky... but not too picky. This is just my 2 cents.