To move an app, you can tap it in App 2 SD, which will open the app's properties in the Application Manager. Once there, tap Force stop and then tap the Move to SD button available in the Storage section. After a few moments, the app will reside on your SD Card.
Of course, unless you have a ton of them installed, apps probably aren't the biggest storage space hogs on your device. Photo and video files tend to take up much more space than apps, so it's worth moving them to an SD Card as well. To ensure that your device stores new photos and videos on your SD Card automatically, open your camera app and navigate to its settings menu (this will vary from device to device).
In the settings menu, navigate to the Storage section, and change the option from 'Phone' or 'Internal Storage' to Memory Card. If you'd also like to move your existing photos and videos, you can easily do so by connecting your device to a PC via a USB cable; the PC should recognize your phone or tablet as a removable storage device, at which point you can move the picture folder from the device's internal storage to the SD Card by dragging it over.
If you would rather complete the process on the device itself without using a PC, open the file manager included on your device (if your device doesn't have one, you can find plenty of them in the Google Play store) and browse to your picture/video folder. Tap and hold it, and in the resulting menu, select Move. Then browse to your SD Card and tap Move Here.
If your Android device won't boot properly or is otherwise unusable, clearing the device's cache partition or restoring it to factory defaults may be your only option. Android-based smartphones and tablets usually come with a built-in recovery tool that you can use to perform some maintenance operations or to restore the device's software to like-new condition. The procedure for entering recovery mode varies from device to device, but it usually entails powering the device down, and holding some combination of buttons while powering the device back on. On a Samsung Galaxy Note II, for example, you launch recovery mode by powering down the phone and then holding down the home and volume up buttons while simultaneously pressing the power button.
Once your device enters recovery mode, you'll see a basic menu containing a few options for applying updates or wiping various partitions. In most instances, you'll navigate the menu with your device's volume up and volume down buttons, and you'll press the power button to select an item. Before wiping all data and performing a factory reset, it's a good idea to wipe the cache partition alone, since this less extreme step occasionally resolves stability issues. Wiping the cache partition removes app components, temporary files, and other random bits of data stored in the cache, but the cache will automatically rebuild with fresh data when you reboot your phone and begin using your apps.
Sign up for Computerworld eNewsletters.