Start testing, applying lessons learned from other digital channels and target early adopters who have been exposed to mobile ads. That's the latest advice from Forrester Research on gearing up for mobile marketing before it goes mainstream.

In a new study, Forrester reports that 83% of marketers believe that mobile will become a more effective platform over the next three years. But at present, consumers' lack of familiarity with the format remains a barrier. For instance, only 7% of mobile users trust ads on their cell phones.

Still, the research firm suggests that advertisers look at the kinds of things people are using their phones for in addition to talking. Some 42% are text-messaging, nearly a quarter are exchanging picture-messages, and 15% are using mobile e-mail.

Furthermore, almost one-third have interacted with some type of marketing on their phones, which Forrester calls a "sizeable minority" that will grow as mobile is increasingly added to the digital mix. Despite frequent claims of high click-through rates for mobile, however, only 1% said they had clicked on a banner ad while browsing on their cell phones, according to Forrester's data.

Marketers are also advised not to be put off by an alphabet city of new acronyms like SMS, WAP and 3G. Instead, they should treat mobile as an extension of other digital formats they are already using.

"Fortunately, interactive marketers already know more about mobile marketing than they may think," wrote Peter Kim, a senior analyst at Forrester and author of the report titled, "US Mobile Marketing: Easier Done Than Said."

That means adapting social media for cell phones in the form of send-to-a-friend messages and referral incentives designed to encourage greater pass-along and adoption. Distributing branded content like logos and graphics so people can customize their default screens and caller ID images is also smart.

Marketers can also extend keyword buys into mobile search on Google and Yahoo, targeting ads based on city, language and wireless carrier. Sponsored links besides search results also have the advantage of being less intrusive than other ad types. For example, 65% of mobile users found an ad that appears while a page is loading to be annoying, compared to only 48% for paid search ads.

Since ads before mobile video clips and games were found to be the least annoying, Forrester recommends running pre-roll spots with mobile video, as is standard for online clips. But they must respect the 15 seconds-or-less rule that applies to video pre-rolls online.

Making sure that mobile sites are useful is also key. That seems intuitive, given the size limitations of the screen and that cell phones are used to get information on the go. But only 23% of users said accessing the Internet on their devices was an enjoyable experience.

To ease mobile surfing, focus on fast-loading content and creating stripped-down versions of regular sites. The Weather Channel's mobile presence, for instance, features ZIP code- or airport-based weather search, dumping the radar maps and pollen counts found on its main site.

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