Ask HN: How do I get involved in open source projects?

I want to get involved in an open source project, but am not sure the best way to do it.

I figured I would just get on github, look for an interesting project, and would start working on it.

But it turns out, most of the projects I have found on github are just a single guy or a small group and they do not have a list of bugs anywhere for me to try to fix. Also, I don't know enough about the software to just start adding features.

How do you do it?