For Ubuntu 14.04, you can just follow the normal ROS installation instructions.

For Linux Mint 17.x, the instructions are mostly the same, here are the steps: http://insane-on-linux.blogspot.com/2014/10/installing-ros-indigo-on-mint-17.html

If you get the following error:

ImportError: "from catkin_pkg.package import parse_package" failed: No module named catkin_pkg.package

Make sure that you have installed “catkin_pkg”, it is up to date and on the PYTHONPATH:

$ pip install catkin_pkg

Error:

ImportError: No module named rospkg

Fix:

$ apt-get install python-rospkg
$ export PYTHONPATH=$PYTHONPATH:/usr/lib/python2.7/dist-packages

This is kinda a hack, haven't bothered to figure out how to properly install python-rospkg to the proper python location for indigo

If you get this error:

ERROR: the following packages/stacks could not have their rosdep keys resolved to system dependencies: ardrone_autonomy: Unsupported OS [mint] 

when running any rosdep command, add the flag –os=ubuntu:trusty to the command.