Two global python packages are all that is really necessary:
sudo apt-get install python-pip
sudo pip install virtualenv
Start virtualenv (used Python3 in this case):
virtualenv <my env> --python=/usr/bin/python3
source <my env>/bin/activate
Save state of virtualenv:
pip freeze > requirements.txt
Install all packages from requirements.txt:
pip install -r requirements.txt
Kill virtualenv (after running source):
deactivate