I once read something on LessWrong which was later labeled The Fundamental Question of rationality: "What do you believe, and why do you believe it?" I have found this useful to adapt to go: when playing, I constantly ask myself, "Are these stones alive or dead, and how do I know that?"

I found it really important to start asking myself a bit broader question, "where do I want to play, and why do I want to play there". If, say, my answer is something like "To prepare the move X", it makes it quite straightforward to play X straight ahead, if it's any good.