Know Your Market

I can't stress enough the importance of knowing as much as you can about your market before launching into it. I don't have any hard data on this, but I'd wager that something like half of business failures are caused by lack of understanding of market realities. (The other half is probably from under-capitalization, but that's another post another day.)

AllBusiness via the San Francisco Chronicle has a good briefing on "What Small Businesses Need to Know about Market Research".  Yes, it takes time.  Yes, it will cost you to do it.  But the less you know, the less successful you will be.  Can you afford not to?