Making things work isn't enough for you any more? Now you need to consider performance and scalability?
Do you hope to some day come with efficient solutions by yourself rather than stumble on many stackoverflow questions to get something done?
Do you feel unqualified to tackle complex tasks with complex data models?
Do you feel that you need to sharpen your sql/active record concepts?
Maybe I can help you!
I send an email each week, trying to share knowledge and fixes to common problems and struggles for ruby on rails developers, like How to fetch the latest-N-of-each record or How to test that an specific mail was sent or a Capybara cheatsheet. You can see more examples on Most recent posts or All post by topic.