Many interesting points have been raised. One that's missing is the question of what you want to get out of learning rails, since that could have an effect on your approach. You can then set about learning what you need to know.
But remember, the best advice is "just do it!" You can't break much.
Paul
Ps did anyone mention irc channels? Also a very useful resourse - especially for finding ppl at the same stage as you whom you can bounce ideas off of.