IF YOU'VE GOT regular customers with shiny new smartphones, then building a mobile application might be right for you. Designed well, an app puts information about your products, discounts and customer service at customers' fingertips, wherever they may roam.

Some marketing experts say apps for iPhone and other mobile devices are the next big thing in small-business promotion, and will become as ubiquitous as the Web site. (See related story, Apps Created for Small Businesses, on new services that help small businesses make apps.) But like a Web site, poor delivery can waste all your good intentions. Here are some keys to creating a small-business mobile app that can help build your business -- and won't just suck your time:

1. Make it truly useful, not just a novelty item. To get on customers' devices – and stay on them – your app needs to provide real value or solve a problem for your customers. "If there's very little to be done with it, what's the point?" says Greg Sterling, a senior analyst at Opus Research Inc. Consider what an app makes possible: better product images, orders with just a few taps, driving directions that make use of GPS technology, click-to-call and -email communication, information pushed out by text message and fun games.

You need, of course, to provide the basics: your address and the opportunity to connect by phone and email. But if that's all you supply, a cheaper mobile-optimized version of your Web site would probably suffice. Keep in mind, an app allows faster delivery of rich content than a mobile Web site does. "The real exciting part here is that you can do a lot more on your mobile app," says Ori Sasson, a general partner at Primera Capital LLC, a venture capital firm that plans to invest in an iPhone app maker. For instance, if you're a pizza restaurant, your app could alert customers that their orders are ready. If you're a medical office, you could send out appointment reminders and give customers the opportunity to confirm, reschedule or advise that they're running late. A Web site, on the other hand, rarely sends an alert "that is directed to you personally, that is time sensitive or location sensitive," he says.

2. Beware the potential pitfalls. While your customers may appreciate alerts about new products, special discounts or your imminent holiday party, there's such a thing as too much information, especially on a mobile device. These mini computers are powerful because they sit in people's pockets, but that immediacy also means it's easy to annoy the people you hope to delight with too many messages or spammy pitches. So don't overstep.

On the flip side, don't create an app that you never update. As with your Web site – and email newsletter, Facebook page and Twitter feeds – your app needs regular care and feeding to remain dynamic and useful. The good news is you can use a lot of the same content in your different digital places – think of it as finding your customers in the place they most prefer, be it their browser, social hub, email inbox or mobile device.

3. Promotion, promotion, promotion. The number of mobile apps are skyrocketing, which means yours can easily be lost in the noise. Moreover, consumers are not yet accustomed to finding and using apps from small or local businesses. And Apple's App Store doesn't contain features that could make it easier for people to find your app, like a search function by city name or zip code.

For now, it's up to businesses themselves to promote applications and get customers to download them. Be prepared to get the word out through your other marketing mechanisms, be it Facebook or a simple sign in your store.

Or, find a wagon to hitch to. In coming months, more apps are likely to emerge that connect customers to myriad businesses near them, says Mr. Sasson. For instance, an iPhone app called iWaffles, as the name might suggest, helps people find places to eat waffles. This week, LivingSocial Inc. introduced an iPhone app called LivingSocial Deals that alerts users in several big cities, such as New York, San Francisco and Atlanta, to one deal each day at a local restaurant, bar, spa, theater, yoga studio or similar business.

Write to Riva Richmond at smalltalk@wsj.com