What do FedEx ( FDX), Hewlett-Packard ( HPQ) and Apple ( AAPL) have in common? They launched during recessions and became hugely successful. If you're unemployed and always dreamed of being your own boss, it might seem like a good opportunity to start a business. But before you get started, be sure to do your homework. Study the market: Look for products and services that more established companies aren't delivering. Big firms are more likely to be distracted by the economy, opening the door for a startup to take market share. Take the long view: When hunting for opportunities, consider where they might lead you in five to 10 years. Famed chef Wolfgang Puck and his company decided to go ahead with a new restaurant at the MGM Mirage ( MGM) and Infinity World Development's extravagant CityCenter in part because they "didn't want to miss the boat," says Tom Kaplan, senior managing partner of Wolfgang Puck. A great idea is only half of it: You should have passion for the concept behind your business. But you must also like doing all the things a business owner must do, such as find customers and handle vendors. "You don't have to love everything you're doing in business, but you have to love the things you do a lot of," says Steven S. Little, author of Duck and Recover: The Embattled Business Owner's Guide to Survival and Growth (Wiley 2009). Little has a friend who started a surf shop because he adored surfing. He discovered that he spent more time talking to vendors and creditors than customers. Keep your operation lean: Create a conservative business plan based on the lowest income possible, and then run it by a trusted business contact. While optimism is an entrepreneur's middle name, the recession demands fiscal discipline.