I usually pick something interesting on github and do the following: 1. pick a feature that i find interesting 2. trace it all the way through, line by line (l

I usually pick something interesting on github and do the following: 1. pick a feature that i find interesting 2. trace it all the way through, line by line (like stepping into a call with a debugger) 3. using an IDE is really helpful because you can click into methods and jump around sources. (especially if docs are attached to sources) look up every function and keyword you do not understand I try to pick a simpler feature first, then if i am still hungry for knowledge I'll pick a more complex one that is related to the first feature.