Sorry, I'm jumping into this a little late just wanted to throw my $0.02 into this discussion. I'm not sure about your level of familiarity with rails, or development in general, but I had a lot of trouble getting started with rails. This leads me to a few pieces of advice. If you have the time don't learn rails 1st. It is oriented around getting things done as fast as possible with minimal amounts of code. This is great in theory but this philosophy makes it difficult to gain a solid understanding of what is really happening in your code base. If you can spare the time for a tangent I strongly recommend playing with something like Sinatra or camping. Sure they syntax is different but try something that forces you to write out the majority of your logic explicitly. Once you have a solid understanding of all the steps rails does for you, and the theory behind them, then learn rails. Personally I picked up and put down rails a couple times because I could not wrap my head around and the things that were being done for me "auto-magically", then I learned a more explicit framework and the pieces fell into place.
Also ignore blogs and advanced rails casts to start with. They are great for adding to your tool-set down the road. However, in the beginning don't worry about haml vs erb, or webBrick vs thin vs unicorn
http://rainbows.bogomips.org/. Build a basic app or two with all defaults then expand, don't learn the latest buzz or gem-set early on it will only add to the confusion.
Last point always remember the problem that rails was created to solve. Its there to build cleanly written apps as fast as possible with minimal boilerplate from the developer. Its made to feel easy and readable, but it is far from the most efficient system out there. Its primary focus is making developers happy not optimization. These days there are a lot of mvc frameworks out there. If you can, get a feel for some others and their philosophies. For instance NodeJS will blow rails out of the water in terms of raw speed, but its code base isn't always as organized and readable on large apps. Basically make sure the tools you use match your needs.