My Rails 3 Tutorial notes that I recommend people use.

rails-3-tutorial-notes

My notes and shortcuts for working with Michael Hartl's great Rails tutorial
(http://ruby.railstutorial.org/)

- Since he has you install RVM in the very first chapter, I recommend actually using it
  immediately rather than getting in the habit of typing out "bundle exec" all of the time 
  or forgetting to create and switch to gemsets. I recommend running this right away:

      $ rvm use 1.9.3@sample_app --create

  This way if you're reading other tutorials too, and want to experiment with gems they
  have you install, you won't have to worry about conflicting gems. Just create a separate
  gemsets for each project.

  Optionally create a .rvmrc file that contains 'rvm use 1.9.3@sample_app' in case you run 
  tmux/screen so you don't have to manually type out 'rvm use ...' every time you open a 
  new terminal, etc.

- If you already know you want to learn HAML or Slim or some other templating language, 
  then I recommend installing them immediately and converting the ERB examples to it. 
  You can always just paste the html.erb code into html2haml.heroku.com to or into
  http://html2slim.herokuapp.com/ to convert to HAML or Slim, respectively.

- You don't have to type 'bundle install'. The 'bundle' command does the same thing. 
  Considering how much we have to type this command, I much prefer simply typing:

      $ bundle

- You don't need to run 'bundle update' before 'bundle [install]'. It's a dangerous habit
  to get into because in real projects you could end up with backwards-incompatible changes
  to your dependencies. Runnig 'bundle update' by itself will try to update every single 
  gem and it isn't necessary if you've already explicitly added the gems to the Gemfile.

- You don't have to type "--skip-test-unit" every time you run "rails new" if you create 
  a file called $HOME/.railsrc and put --skip-test-unit in it.

- You don't have to type 'heroku create --stack cedar'. The cedar stack is the default in
  Heroku, so you can simply type 'heroku create'.

- At the time of this writing, the tutorial uses a 1.x version of capybara, even though 
  2.0.0 has been out. The reason for this seems to be because capybara 2.0 broke the
  has_selector helper that the tutorial uses and isn't fixing it until 2.1. You can
  read about this here: https://github.com/jnicklas/capybara/issues/844

  The tutorial will confuse you when you switch to 2.x because capybara no longer places
  specs in specs/requests but instead puts them in specs/features. I recommend using the
  exact 'old' version of capybara the the tutorial recommends, for doing the tutorial.
  For your own projects, if you want to use 2.0, you'll get errors about 'visit' method
  missing. However, the rails integration_testgenerator still puts things in spec/requests,
  so do:

      $ mv spec/requests spec/features

  You'll also need to not put rspec-rails 2.11.0 in Gemfile, but will need a higher 
  version, or you'll also get errors about 'visit' method missing. So instead use:

      gem 'rspec-rails', '>= 2.11.1'

  Or you could put the following line in spec/spec_helper.rb in the RSpec.configure

      config.include Capybara::DSL

  And you will also need to edit Guardfile and change 'requests' to 'features'.

- I don't recommend using spork. It's not much faster usually and many people find it
  too buggy and annoying to work with. If you really want to bootstrap a rails environment
  up front, there are potentially better methods such as https://github.com/jstorimer/spin.

- When using bootstrap-sass you rarely should just add Twitter Bootstrap's classes directly
  in your HTML, since that makes refactoring away from Bootstrap harder later (and bootstrap
  is just a 'bootstrap' afterall, not something you'll want to be tied to forever). Since we
  are using SCSS we have access to mixins. This means, instead of doing things like:

      <header class="navbar navbar-fixed-top navbar-inverse">

  we can make our *own* CSS class, say header-nav bar:
  
      <header class="header-navbar">
  
  and use the @extend directive to inherit Bootstrap's LESS-based CSS classes. (make sure you
  have @import "bootstrap"; or you won't have access to Bootstrap's styles, mixins and
  variables. So in custom.css.scss (or application.css.scss or wherever you're styling from):
  
      .header-navbar {
        // Use Twitter Bootstrap's navbar component
        @extend .navbar;
        @extend .navbar-fixed-top;
        @extend .navbar-inverse;
      }
 
  Later if you decide to stop using Bootstrap you won't have to grep your html for all of the
  possible different Bootstrap classes to replace!