Facebook Mobile leaves you more susceptible to attempted hijackings and identity theft. Make sure that you don't lose your private and personal data to intruders.
Lock your device. You should always have a passcode or pattern on your phone. You can also set your phone to delete its data after a number of failed attempts to break the passcode. Use a different password for email and Facebook accounts. Take the time to invent multiple passwords for your accounts. Make sure Secure Browsing is on. Avoid unprotected Wi-Fi. Enable login notifications and use "Trusted Contacts."
These should help you to protect your account from hackers and ID hijackers.