Since you already know some Python, sign on to Udacity's (free) CS 212 Design of Computer Programs by Peter Norvig. It has 7 weeks worth of classes and teaches you a tonne in that time. It is a class targeted specifically at "I know some basic programming but what do I do to get to the next level?" people.
The official version of the class is over, but nothing stops you from joining today, watching the videos, doing the assignments etc.
Since one of your aims is to 'learn from great coders' this should be right up your alley since Peter is one of the best developers in the world and you can see him developing multiple programs and refining them step by step till they are gems of elegant code, and you can trawl the forums to see questions people asked and answers to them.
Once you work through the class - should take you 7 weeks if you are disciplined -and you understand all the techniques demonstrated there, you'll be in good shape to start/join an open source project in a domain of your interest.
And oh prepare to have your mind blown. Peter Norvig is one seriously good developer.
Good Luck.