What is the proper way to manage multiple python versions?

I have a machine with Python 2.6 installed as the default Python. Then, I installed Python 2.7, and manually created /usr/bin/python as a symlink to the new installation. Then, I was running into problems with command-not-found . I'm trying to reinstall it: sudo apt-get remove command-not-found and I get this error: /usr/bin/python does not match the python default version. It must be reset to point to python2.6 But I really want Python 2.7 to be the default. How do I fix this mess?