How do I install Ruby on Rails on OSX?

Easy, use Rails Installer

You also want to install Xcode and a package manager in order to install certain gems.

On OSX there are two choices for a package manager

• MacPorts is modelled on Debian's apt package manager. It has a large package selection.
• Homebrew is newer than MacPorts and seems to be more popular amongst Rails users.

Either one is fine.