Make sure to backup all your files, all your database content, installers and config files, and basically anything you'd need to rebuild everything you care abo

Make sure to backup all your files, all your database content, installers and config files, and basically anything you'd need to rebuild everything you care about from the bare metal. For websites, a periodic file dump via FTP, and database dump via a MySQL script is nice and easy. There are also Wordpress plugins that will do the dump and email it to you regularly.