How do I make my Linux PC mount my Android 4.2.2 phone using MTP?
I've written a tutorial on how to get MTP devices recognized under Ubuntu.  If you've already installed mtptools and added the udev rule, you still need to create a static mount point for your device and let mtp know that's where it lives.  Make sure you've restarted either your computer or the udev service since you added the udev rule (sudo service udev restart), and then


sudo mkdir /media/MTPdevice (call the directory whatever you like)
sudo chmod 775 /media/MTPdevice
sudo mtpfs -o allow_other /media/MTPdevice


Attach your phone (make sure it's unlocked, if you have a pin or swipe pattern).  You should then be able to see both the internal and external cards.  Note that you won't be able to open files directly from the cards, you'll need to copy them locally first.