At my work, I am required to follow the house style for indentation, which goes as follows:
there are many ways, but here's a simple, easy to understand way. add these lines to your ~/.vimrc:
~/.vimrc
autocmd FileType html setlocal ts=2 sts=2 sw=2 autocmd FileType ruby setlocal ts=2 sts=2 sw=2 autocmd FileType javascript setlocal ts=4 sts=4 sw=4