Take the guesswork out of product development and sales with these tips from folks who are doing it.

By Susie Boghosian and Jinny Fleischman

To avoid that competition, you might consider working with a manufacturer to modify existing merchandise — putting a special cover on an existing book, for example. By modifying existing products, you’re not obligated to pay for creative and manufacturing costs, which already have been borne by the manufacturer. One of the advantages of this type of merchandising is that you can set your own price and not be in competition with general retailers.