If you're doing more than one project on your machine then you need to concern yourself with dependencies across projects. In python the old-school way of doing this is to use virtualenv and pip. These tools get the job done, but they may have some caveats you should be aware of.
Virtual environments can be tricky if you're not careful.
Feedback? See an issue? Something unclear? Feel free to mention it here.
If you want to be kept up to date, consider getting the newsletter.