Mobile marketing is gaining momentum, even in a down economy. One in four US interactive marketers is currently using mobile, and nearly half of these (47%) will increase mobile spending this year. Even with marketers using a wide variety of tactics, three out of four consumers with mobile phones have yet to see an ad. Best practices for mobile marketing: 1) Identify your target audience's mobile habits; 2) master the tools of mobile to get up to speed; 3) execute simple campaigns to start; and 4) adapt to evolving measurement standards. Even as marketers master these skills, they'll face new challenges like how to reach a mobile audience that may become fatigued by the amount of pitches.