If you are reading this, it most probably means that you have already installed Latex-Suite and the help files. If this is not the case, follow the detailed instructions on Latex-Suite's download page.

Make sure that you create a few necessary settings in your ~/.vimrc.

" REQUIRED. This makes vim invoke Latex-Suite when you open a tex file.
filetype plugin on

" IMPORTANT: win32 users will need to have 'shellslash' set so that latex
" can be called correctly.
set shellslash

" OPTIONAL: This enables automatic indentation as you type.
filetype indent on

" OPTIONAL: Starting with Vim 7, the filetype of empty .tex files defaults to
" 'plaintex' instead of 'tex', which results in vim-latex not being loaded.
" The following changes the default filetype back to 'tex':
let g:tex_flavor='latex'

In addition, the following settings could go in your ~/.vim/ftplugin/tex.vim file:

" this is mostly a matter of taste. but LaTeX looks good with just a bit
" of indentation.
set sw=2
" TIP: if you write your \label's as \label{fig:something}, then if you
" type in \ref{fig: and press <C-n> you will automatically cycle through
" all the figure labels. Very useful!
set iskeyword+=:

In the unlikely case that Latex-Suite is installed, but you do not want to use it (e.g., if it is installed system-wide and you use some other package to deal with tex files), you can suppress the loading of Latex-Suite by setting

let b:suppress_latex_suite = 1

in your ~/.vim/ftplugin/tex.vim.