I was thinking along similar lines. Paul Graham has done a good job of laying out what the major factors are in building a successful startup, but to pinpoint d

I was thinking along similar lines. Paul Graham has done a good job of laying out what the major factors are in building a successful startup, but to pinpoint down to one single factor being the MOST important is really just an exercise in understanding your own weaknesses. For some people, picking a problem you understand is the obvious part, but being flexible about their company's focus is not so obvious, so for them, that will be the most important principle. The most important principles for the individual are the ones that they won't accomplish naturally without thinking about it and working at it.