When developing a new site or adding features to your old site, it's always a good idea to do frequent database "development" backups (as opposed to normal "everyday" backups that you're already doing, right?) While there are a bunch of different methods for performing a backup (via the command line, phpMyAdmin), one of the easiest is with the Backup and Migrate module.
One thing that consistently trips up both new and experienced developers when enabling a new module are "permissions". I can't tell you how many times I've enabled a new module then cursed my computer for a few minutes thinking that the module wasn't working properly - only to realize that I forgot to set some arcane permission on the admin/user/permissions page.
So, next time you download and enable that shiny new module, be sure to not only configure it using its settings page, but to check its permissions!