According to some estimates, smartphones—packed with personal data, always connected, and largely unsecured—are now being infected with viruses at twice the rate of PCs. Malware disguised as a legitimate app can steal account information and direct your phone to call or text expensive premium-rate numbers or to send spam texts to your contacts. Links, which are often cut off in phone browsers (making suspicious ones hard to spot), can send users to sites embedded with malware.
Mobile antivirus programs made by Kaspersky and Lookout work fairly well for preventing smartphone infections, but there are other steps you can take. To avoid Web-borne viruses, think twice before you click on text and e-mail links. Instead, go to your browser and manually enter the address. A quicker option is to install a lesser-used browser such as Opera or Skyfire, which aren't as likely to be targeted by virus writers.
On the app side, look at the manufacturer page and reviews before you install or update an application. It's also worth spending an extra minute to check out viaForensics, a site that runs security tests on popular apps and rates them. And set permissions cautiously: If an app requests access to your contacts, ask yourself why. Finally, for an added layer of security, download an encryption app, like Firebox ($6 for iPhone) or APG (free for Android). They encode passwords, files and other information, then require a security key for access.