This is a small feature on my personal, small - but effective - setup for mobile security. For securing my smartphone.

First of all, I am using an Android device, but I am certain that equivalent programs exist on iOS and probably every other OS as well.

This is basically what I got:

The reason for this setup is that - while the android lock pattern technically is quite secure - often the pattern can easily be spotted as a set of smeary wipes on the display. Not really an option if you want your data protected!
Furthermore I do not like the hassle of entering it all the time, so comfort was part of my motivation as well.

The Setup:
So what I did, was combining two, quite secure, methods of unlocking to a very comfortable, easy and safe unlock system:
While my Pebble is connected (using low-energy 4.0 Bluetooth) an App on my Nexus (Pebble Locker) ensures that I do not have to enter any pin-code at all. So as long as everything works as it's supposed to, I never ever have to enter any unlock pin or pattern.

In case of failure, (leaving the pebble at home, having it's battery die...) I have a NFC-Tag in my wallet, that can unlock my phone as well. The NFCLockScreenOffEnabler App allows me to use the ID of a specific tag (you have to register it once) to bypass the unlock screen as well. So if my Pebble-Unlock fails, I can always just move the NFC-Tag to the back of my phone and unlock it using the tag.

For a unlock without either of those, I set up a password using a randomly generated 256 character string. Good luck brute-forcing this. I added it to my KeePassX key-chain so I wouldn't lose it.
I did have to enter it a few times, after updates when everything was broken, but that was always my fault - never change a running system... and I lived through it. For easier access you could just use a pass phrase, but that did not feel as secure as random gibberish...

Anyways - I have been using this now for about half a year and am very, very happy with the setup. I wouldn't want anyone getting all my private data, - my messages, emails, photos maybe even my login data. Using your smartphone everyday a lot of personal stuff will be stacking up. Take measure to protect it !
Setting this up may cost a few hours, but you will be glad you did it, if anything ever happens to your phone.