Or, if you only want to use these settings for python files, create a ~/.vim/ftplugin/python.vim file. Mine looks like this:

  setlocal tabstop=4
  setlocal softtabstop=4
  setlocal shiftwidth=4
  setlocal textwidth=80
  setlocal smarttab
  setlocal expandtab
  setlocal smartindent