marketplace and writerly play

The question beginning writers always seem to ask is, where do you get your ideas? There's not really a good answer for this, because most writers have lots of ideas. The real problem is, how do you figure out which idea is the best one to write right now. Which one are you suited to write? Which one is marketable at the moment? Which one do you have the skills to write? When you've done it a lot, you get a sense of it, but that doesn't mean that you don't still make mistakes.

I think th...