Try to get into a bugmash of some kind. I started this way with Rails and I wrote about it http://www.rohitarondekar.com/articles/my-first-rails-bugmas...

Many companies and tech groups have these around the world during meetups and conferences.

But most importantly dont let this pull request fool you. Rails is nice to contribute to even if you are starting out and the rails core team especially jose valim and santiago pastorino are super helpful.