The 11 Pitfalls of Startup by Brad Sugars (Entrepreneur.Com)

http://www.entrepreneur.com/startingabusiness/startupbasics/startupbasicscolumnistbradsugars/article167930.html

I am suggesting this article because it is a good read. This article lists 11 Start-Up pitfalls. Brad Sugar seems to know what he's talking about.
My favorite tip is tip #12 (I know, it says "11" but there are twelve). But anyhow, this tip offers the advice of cultivating business relationships. Your customers/clients should not be a one-time deal. A relationship should be built over time by you providing then with exceptional service and them being a constant source of business because you are so darned professional.