Here is the procedure that I normally follow for installing and configuring a fresh Ubuntu 14.04 server to host multiple Drupal websites:
Login as root, and run the following commands:
shutdown -r now
Add a new user to host the Drupal websites:
Grant sudo permissions.:
sudo usermod -a -G sudo USERNAME
Then login as that user, and run the rest of the steps listed below.
Install latest git from official PPA: