In his essay Before the Startup, YCombinator’s founder Paul Graham explains that because startups are counterintuitive, you can’t always trust your instincts when starting a startup. Then he gives a list of 5 things you can do to prepare yourself for the task.
For example, where to get ideas for a startup? Not by making an effort to think of startup ideas, but by (1) learning a lot about things that matter, then (2) work on problems that interest you (3) with people you like and respect.
The whole essay is worth reading.