No matter how bad of a web design client you have faced, there is always a worse one right around the corner. Dealing with the various personalities of web design clients is harder than any technical glitch on any computer program, so get yourself ready for everything that you must go through with people in order to have a successful web design business.
The bottom line is this: Most of your web design clients will not know what they want, even if they tell you that they know exactly what they want with a straight face. Invariably, if you give it to them, they will decide on something else, wasting your time with endless revisions, or completely reject what you present to them, even though you are simply copying what they had in mind.
You must also make sure that you are talking to the right person before you begin. There is nothing worse than doing the work of an underling only to find out that the boss hates it.
From: Top Web Design Schools