Before they hunt for the perfect cantaloupe or the right pair of khakis, shoppers make another choice: where to shop.

For retailers, the decision can mean the difference between boom times and bankruptcy. But low prices and a wide selection of merchandise aren't enough to win this competition. To succeed, a store and its surroundings must offer the sort of comfortable and hassle-free experience that encourages people to show up and spend.

It's hardly a science, but experts say there are key elements in any winning retail formula: meticulous planning, input from neighbors, and a group of landlords fluent in the psychology of shopping and design. That formula -- and the stakes involved in getting it right -- is explored in the next few pages with a look at two local retail areas.

On the surface, the Ballston neighborhood of Northern Virginia and Van Ness in the District have much in common. Both are home to tall, modern buildings and wide roads. Both cater to thousands of office workers. For years, residents of both neighborhoods have jumped into their cars and driven elsewhere to shop. As consumer destinations, both have been deemed failures.

But Ballston is attempting to revive itself, and those efforts are showing dividends. With prodding and guidance by local activists, business leaders and the Arlington County government, retail space has been renovated and popular shops, restaurants and entertainment venues have moved in. Even non-Ballstonians are showing up to open their wallets. The stirrings show how a coordinated campaign and a little forethought can breathe life into an area considered beyond help.

Van Ness, on the other hand, continues to stumble. Storefronts stand empty there for years, although they're located in one of Washington's busiest commuter lanes, and stores that endure tend to be fast-food joints and chain stores, neither of which lends the place original character.

The chief problem is the layout and buildings, which were conceived in the 1960s as part of a lamentable architectural fad. Multiplying the woes, landlords don't strategize together in Van Ness, and a tiny band of activists fights any developments that might draw crowds and increase traffic.

With planners here and elsewhere scrambling to revive urban shopping, the troubles of Van Ness and Ballston's nascent comeback illustrate the stakes and the rules in the multimillion-dollar world of retail design.

CAPTION: A sign at the University of the District of Columbia should perhaps have a companion showing that the school's home neighborhood, Van Ness, is a "Shopper Free Zone"; the retail revival of Arlington County's Ballston community is evident in the lunchtime crowd at the food court at Ballston Common mall, which is undergoing an expansion.