Linux kernel is one of the biggest open source project. It has more than nine millions line of codes with more than 1000 developers are working distributed around the world. For some people, joining this massive groups would require lots of guts, but Jonathan Corbet, LWN editor has make it easier by making a documentation about How to Participate in Linux Community (Linux kernel in this case).
It gives you detailed about what the project are, how the process works, early planning and up to the phase when you will work on your own and start sending your patches as a result of your contribution to the project.
Kernel hacker wannabe? You must not miss this guidance