If your device has a SIM inside you should also set a SIM lock. This is an additional 4 digit pin that controls usage of the SIM card independent of the device which prevents thieves from putting the SIM in another unlocked device to make calls on your account.
Ensure your important data is backed up somewhere, such as a PC or in the cloud.
If you have an Android device it is recommended that you install reputable anti-virus software on your device.
If you have an Android device make sure it is set up with the Android device manager. This will enable you to remotely locate or wipe the device if it is lost or stolen.
iOS users can do the same with iCloud and 'Find My iPhone' to track, lock and wipe devices.
Always use a strong password for your app store account. These passwords are high value due to them usually being linked to an account with credit card details. Try to use a password that is at least 8 characters, and contains upper case, lower case, numbers, special characters such as punctuation and doesn't contain a word found in the dictionary.
Security mark your device with an ultraviolet pen.
Thieves operate on campus. Do not leave your valuables unattended for even a short time.
Be aware of your surroundings when using your mobile device. If you are off campus and feel threatened you can go to one of the student safe spots for help.
If the worst happens and your device is lost or stolen, wipe it and report it to your mobile phone network and the police as soon as you can.