TL;DR for http://docs.python-guide.org/en/latest/dev/virtualenvs/
** install virtualenvwrapper
export WORKON_HOME=~/Envs
source /usr/local/bin/virtualenvwrapper.sh
configure env
mkvirtualenv my_project
start working
workon my_project
More!
create a virtual env with a specific python version + preinstall requirements
mkvirtualenv --python=`which python3` -r requirements.txt <env-name>