I don't have a system per se. A few of the podcasts I listen to will often have some influence on me. For instance, in listening to (I think) Patrick Klepec talk about his experience with Singularity, I began my Summer of the B-game (Singularity, Dark Void, Dead Space, to name a few). I am hesitant to put Dead space there, but it felt (in spirit if nothing else) like it belonged on that list. That game led me to try the rest in the series.
There are other games that I couldn't get to this past summer that are on my B-Game list, such as Lost Planet, but time was not on my side.
Right now, I am between moods which has actually resulted in my not playing any games for the last month and a half. The last game I played was Deus Ex: Human Revolution (another B-Game?). I enjoyed it so much that I just haven't found another game that I wanted to play for a bit. I tried to play Max Payne 3 (certainly another B-game), but the gameplay wasn't appealing to me, so I have essentially stopped.
I don't mind these lulls, but I am looking forward to getting back at my backlog soon. Who knows, as I peruse the goty lists from 2013, something might strike a spark and get me playing again.