How To Be A Good Open Source Community Member

A friend of mine who is a very talented writer recently became intrigued with open source and asked me to help her to understand how to be a good open source community member. Open source is one of the most unusual things in the world. Is there any other profession where highly skilled professionals donate their free time to give their work away for free? Many spend long hours at their day jobs, just to spend their nights and weekends doing the same thing.