To begin, download the latest stable version of MacVim. Move the .app to your Applications folder.

Make sure you have a ~/.bin folder and it is included in you PATH variable in your .bash_profile file.

In your .bin folder create the following script named gvim and make sure you chmod +x the file.

#!/bin/bash
if [ $# -eq 0 ]; then
	# just open GVim
	open /Applications/MacVim.app
else
	# create the file if it does not exist
	if [ ! -f "$1" ]; then
		touch $1
	fi
	# open the file with GVim
	open $1 -a /Applications/MacVim.app
fi

Next create your ~/.gvimrc file. Example file:

set backspace=indent,eol,start " allows all proper backspacing
set vb " visual beep
set lines=56
set columns=92
set anti " antialiasing on
set gfn=Monaco:h12 " set the font and size
colorscheme torte " set the colorscheme to torte, if torte is not found, use billw
set guioptions-=T " removes toolbar