Python's packaging system was and is still sometimes somewhat broken. However, it's getting better: compilation related issues are rarer nowadays thanks to the wheel pre-built package format (https://www.python.org/dev/peps/pep-0491/). Another great thing is the manylinux tag (https://www.python.org/dev/peps/pep-0513/) which allows to create portable packages which are compatible with many distributions + contain all required dependencies. For example, I didn't want to compile anymore OpenCV all the time by myself so I made it available as wheel package in PyPI: https://pypi.python.org/pypi/opencv-python

If on Windows, google Christoph Gohlke's (spelling?) big list of pre-compiled Python modules.

How do I know to do that? Most projects just say "Install OpenCV" or, if you're lucky, give you the step-by-step for doing a pip install. Assuming you already have pip.

I remember the first time I sat down to really do something with python, step 1 was setup a virtual environment...

I never got to step 2 that week

>How do I know to do that?

The answer, unfortunately, is: you don't - at least not from the docs of all libraries you are trying to use. Maybe from some.

I found it by googling - so shared it, since it might help you.

A less than perfect system, I know.

Yes, I remember that installing pip itself was slightly tricky or involved, a while ago. I think they have made it simpler in recent versions, and it also comes pre-installed with some Python versions, likely 3.x and recent versions of 2.x.