We can’t stress it enough, BACK UP, BACK UP, BACKUPPPPP!!!
The guys over at iThemes and their plugin Backup Buddy make it easy. Here is a quick description…
BackupBuddy is an all-in-one solution for backups, restoration, and migration. Back up to your server, Amazon S3, a FTP/FTPS account, or an email. Use the backup with the Importing & Migrating script to quickly and easily restore your site on the same server or even migrate to a new server with a different domain and database. Whether you’re an end user or a developer, this plugin is sure to bring you peace of mind and added safety in the event of data loss. Our goal is to keep the backup, restoration, and migration processes easy, fast, and reliable.
This is a pay plug in, but well worth the money!
Learn more at http://pluginbuddy.com/purchase/backupbuddy/