There are two other folders you want to backup. The first is your theme folder to make sure you have a backup copy of any customizations you may have made. The second is your uploads directory so that, if you need to change hosts or if things get deleted, you have copies of all the images. This way, your blog doesn't have a bunch of broken files.

You need to be able to automate an FTP job. If you're a skilled programmer, there are lots of ways to skin this cat. If your programming lacks some mojo, there are options: for Windows, use Syncback SE; for Mac, use AASync. Set up a scheduled job (one for each folder) and create a copy on your hard drive. I like to use my file server instead of my desktop so I don't have to worry about leaving it on.

Lastly, to bring things full circle, if you have lots of data or critical data, it's important to have an offsite backup. I move all of my files to my file server every night. I have Carbonite running on that server so everything has an offsite backup. Lastly, just to make sure things are functioning, set a once a moth reminder for yourself to check that your backups are running. Sometimes things break and the time to know about it is before the crisis. A once-a-month check is easy enough to do and give you a lot more peace of mind.