What I actually find most important is being able to do a well worded google search (I sometimes wonder if there should be a qualification for that in itself lol?). The Ruby and the Rails forums are very friendly and helpful.
I usually start a google search with Ruby or Rails and the version number, followed by a question that tries to avoid using common phrases.
Finding a past thread relating to something you are trying to achieve can very often lead to an excellent discussion with different approaches to doing things. I nearly always find someone has written something worth reading.
How you go about learning, also depends on your main goal. Is it to get an app up and running, or is it to become more proficient as a programmer (I am guessing probably some of both)
Occasionally digging into some existing code can highlight areas where you may want to improve your understanding. Particularly when thinking about how to structure a program.
If you want to learn Ruby, then any Ruby based framework is likely to help, although I only have experience of Rails. What I do think is that Rails opinionated approach can help you to formulate some good approaches to your own development.
Using a framework is a great way to build an app, but may not be the best way to get to understand how to develop in an object orientated way. For this, following the tutorial in the Ruby Book, is a start. What I found great fun and very challenging was developing a small app using GTK2 and Ruby. With GTK you can build a small window based app, although getting your head around the API can be a bit challenging. But starting something from scratch is useful to get to understand how to structure your folders, where to put your code and how to define and build objects etc.
Just my thoughts!