The would-be entrepreneur's handbook

A good idea is only a good business opportunity if people actually want to buy what you've got to sell. "It's all about making the world a better place for the customer," says Shane. "If you solve a customer need, you will be rewarded. If you don't, you'll have a hard time staying in business."

The most amazing idea may not be a viable business for any number of reasons. Customers might not perceive a need for it, for example. Or there may be too many players already.

The best way to find out if prospective customers will buy in? Ask them. Check out SurveyMonkey.com, which enables you to build, send and tabulate results of an online survey. (You can collect 100 responses for free and 1,000 for $20 a month.)

For a survey to be useful, you've got to send it to the right people. Contact a relevant trade association to see if the group knows of a targeted list you could buy (cost: about $75 to $125 per 1,000 names). Or befriend a blogger in the field, and ask that person to link to your survey, Slim suggests.

Don't forget to ask potential clients these key questions: How much would you pay for this product or service? And how often would you buy it?

NEXT: Step 5: Write a winning business plan