Do these first:

• Install Homebrew

  # In your Mac Terminal, run:
  $ ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
  

  # In your ~/.bashrc, ~/.bash_profile, or ~/.zshrc (for zsh users)
  # ...
  export PATH=/usr/local/bin:$PATH
  

  $ brew doctor
  

   [full instructions]
• Install the latest Mac C and C++ compilers

  # Get the latest version of Xcode from the Mac App Store
  # Here: https://developer.apple.com/xcode/
  

  # Open Xcode, then press `Command + ,` to open preferences
  

  # Click `Downloads` at the top of the window
  # Then click `Install` next to `Command Line Tools`
  

   [full instructions]

Updated 2013-09-15: Add Xcode compilers as a dependency.

# MacOSX-specific instructions
$ brew update
$ brew install git

# If you get an error:
# `Warning: /usr/bin occurs before /usr/local/bin`
# Then add the following to your shell profile (.bash_profile, .zshrc, etc.)
export PATH="/usr/local/bin:/usr/local/sbin:~/bin:$PATH"

# Make sure you are using the right git binary
$ which git
# should be "/usr/local/bin/git"

# Configure git with your name and email
$ git config --global user.name "Django Reinhardt"
$ git config --global user.email "man_with_guitar@hotmail.com"