Paul Graham, founder of Y Combinator, wrote this essay almost ten years ago.   It seems that his observations still hold true today:

The 18 Mistakes That Kill Startups

October 2006[[[[[[[[[[[[[ In the Q & A period after a recent talk, someone asked what made startups fail. After standing there gaping for a few seconds I realized this was kind of a trick question. It’s equivalent to asking how to make a startup succeed-if you avoid every cause of failure, you succeed-and that’s too big a question to answer on the fly.