Clone it :

git clone https://github.com/mgedmin/dotvim ~/.vim

If your vim is older than 7.3.1178, you'll also want to run :

~/.vim/install.sh

Then install all the plugins (this'll be an interactive) and compile C extensions for things like Command-T and YouCompleteMe :

make -C ~/.vim

Don't put any lines in your .vimrc that you don't understand.

Browse for ideas, copy interesting snippets. One by one.