One of the best books I have read lately is a book by Edward DeBono called Six Thinking Hats.  The book suggests an interesting technique that can be used in group decision making exercises.  It is easy to understand and easy to use but its results can be powerful. 

Each of the six hats have a different color designed to represent the perspective that its "wearer" is asked to adopt when approaching the issue at hand. 

The best way to find out your potential clients and customers want is to ask them.  Tools like Survey Monkey and Zoomerang have made that easy.  They manage the process and give you a good format for asking different types of questions.