Ask HN: How can a beginner start contributing to open source?

I love programming, particularly solving problems using algorithms and data structures. I don't have a firm gasp over any language, but choose to work with C++, Java and Python. Whenever I try to get into open source, I realize the projects to be immensely big and very complex and end up looking for something simpler. But this goes on and on. So my question is, How can a beginner start his/her journey into the open source? What path would you recommend?