Dude, take a step back and forget that you know this stuff already and do it professionally. That list is not easy and far from obvious, even for real programmers coming from other environments, let alone for actual programming beginners.
Your list is far from canonical even at this very moment and hasn't even been common for very long. To figure out your list, I have to:
1) know that homebrew is the "right" way to install software that rails depends on, rather than MacPorts or Fink, or the Mac app store, or download.com, and oh yeah, there is this thing called sudo, and I should install homebrew recipes using it, or should I??,
2) know that rbenv and ruby-build are things that exist and that they are competitors to RVM but are either more or less in vogue depending on who I talk to,
3) understand that rbenv doesn't just work in the current shell without closing and re-opening it,
4) know that the "right" version of ruby to use is 1.9.2-p290 (I have to know the patch-number?!) and that I need to install it and set it as my local version (wait, what does that mean, why do I need a local version?),
before I can get around to actually installing rails and using it.
Now, I could just blindly follow someone's list from a blog post (randomly chosen presumably, because the theory here is that I don't know enough about these things to make an informed decision). Maybe I would even get lucky and find a list that works properly with the version of rails that the official documentation is talking about, but it would still be a much better experience by far to go to the official rails site and be told: "hey, download this all-inclusive, up-to-date, guaranteed to work disk image straight from us!".