The first step is to download Prey from Google Play and install the app on the device you want to protect. A free Prey account allows you to monitor up to three devices at once.
Once Prey is set up on your device, you'll be prompted to log in. If you don't have an account you'll need to visit the Prey website to create one.
At the Prey website, click Devices at the top-left of the page to see a friendly overview of the devices the software is protecting for you.
You can specify which reporting options you want to use. If the device you're protecting is a laptop, you'll see additional options here, such as capturing periodic images from the webcam and monitoring updated files.
When your device is lost or stolen, you can activate Prey's monitoring features by sending an SMS - assuming it's a phone you're dealing with - or simply by logging into the Prey website, flicking the switch to "MISSING" and clicking the green button
You'll receive regular reports showing your device's location and other useful information. By default, an email is sent out each time a report is received, which could warn the thief he's being watched: you can turn this off under Account settings.