As I said in another recent comment, most OSS coders start off bad; it's being part of the community over time that makes them good. So get a couple sets of asbestos underwear for when the first flames roll in and start small. Find something small that annoys you, fix it, generate a diff (if you don't know how to do this, figure it out, it's easy and will win you a few points right off the bat) and send it to the mailing list. Rinse, wash, repeat, for increasingly large values of "small". :-)