Though Facebook, Twitter and a host of social networking sites are hugely popular among young and old alike, businesspeople who market to other businesses once ignored social media to their detriment.

No more. Many are now experimenting with LinkedIn, blogs and Webcasts, but they often still miss a key point: Companies don’t join communities — people do — and if you sell to businesses, you should recognize your customers may already be part of a community that shares certain characteristics.

Indeed, the trade journal Marketing Business Weekly contends that most business marketers don’t effectively use social technologies to influence the purchasing decisions of their customers. Can this be fixed?

Many marketers jump to the new technology without first asking fundamental questions about their customer base. To begin, it is essential that you understand your customers, appreciate the social media they are likely to use and begin to develop a plan to reach them. Your customers may publish a blog or Web page, contribute to online forums, join Facebook or just read blogs or online reviews.

By profiling customers and using the information to construct social media tactics that complement the rest of the marketing mix, business marketers can begin to change the nature of the marketing relationship.

This is particularly important because it is becoming more difficult to reach high-priority customers as markets become more fragmented and distribution channels become more complex. Social media allows another touch point that enables a closer and more personal relationship with customers.

Business marketers sometimes find it difficult to justify spending money on social media , fearing a paucity of reliable ways to measure success. But to shy away from such efforts because outcomes are difficult to measure avoids the real issue. Social media is less costly to implement than a full-blown communications strategy, so why not try something? Experiment and see what the results are.

The type of social media used depends on both the customer’s needs and the marketing objective. Regardless of how their customers use social media, marketers must also determine the marketing objective before deciding whether social media can help accomplish the company’s goals. For companies launching a new product, generating awareness and providing product information are key priorities. Alternatively, companies with established customer relationships may focus more on account maintenance. Marketers need to understand how social media will change their relationships with customers and prospects, and then select ways to measure these changes.

The final step in the planning process is to pick the technology that will fit the marketing strategy. Not every social media tactic works in every situation, so marketers must carefully choose the tactic that will best enable them to develop a valuable relationship with their customers. Using the example of a company launching a new product, social media can help generate awareness and interest through tactics that are more viral in nature. For instance, posting a clever video on YouTube, launching an application on Second Life or “leaking” information on industry blogs can get a company attention from people outside its typical marketing reach. On the other hand, providing account maintenance is better suited for brand-based social networks or blogs. These types of sites can serve as one-stop shops for customers looking for product information, customer service or a place to give feedback.

As with any communications strategy, effectiveness is a function of fit — whether the message and customers’ information requirements are aligned and provide the answers that motivate the buyer. Given the interactive nature of social media, one’s ability to maximize the benefits of such interaction may depend on the appropriateness of the message and the tactic used to reach the target audience.

>> University of Virginia’s Darden School of Business Professor Robert E. Spekman will co-teach Darden’s Executive Education course “Strategic Marketing Management” Sept. 23-27.