Lange, multinational corporations may be the companies whose ups and downs seize headlines, (1)But to a far greater extent than most Americans realize, the economy's vitality depends on the fortunes of tiny shops and restaurants, neighborhood services and factories. Small businesses, defined as those with fewer than 100 workers, now employ 60 percent of the workforce and expected to generate half of all new jobs between now and the year 2000. Some 1.2 million small forms have opened their doors over the past 6 years of economic growth, and 1989 will see an additional 200,000 entrepreneurs striking off on their own. Too many of these pioneers, however, will blaze ahead unprepared. Idealists will overestimate the clamor for their products or fail to factor in the competition. Nearly everyone will underestimate, often fatally, the capital that success requires. (2)Midcareer executives, forced by a takeover or a restructuring to quit the corporation and find another way to support themselves, may savor the idea of being their own boss, but may forget that entrepreneurs must also, at least for a while, be bookkeepers and receptionists, too. According to Small Business Administration data, 24 of every 100 businesses starting out today are likely to disappear in two years, and 27 more will have shut their doors four years from now. By 1995, more than 60 of those 100 start-ups, 77 percent of the companies surveyed were still alive, (3)Most credited their success in large part to having picked a business they already were comfortable in. Eighty percent had worked with the same product or service in their last jobs. Thinking through an enterprise before the launch is obviously critical. But many entrepreneurs