external hdd, more space, easy to find, hard to lose can break when moving it a lot when transferring files.
usb, less space, easy to lose, can break when unplugged when saving something.
I backup using a RAID 1 array. If one drive fails, I'm still safe, and can just replace the broken drive.
Its not very likely, though possible, that 2 drives will go at once.
Do you have another computer? You could cross-backup them. Data from A backed up on B and vice-versa. That's what I do with my brother. We back-up everything through the network.
To be honest, there isn't that many backup solutions for the home user, except for getting another drive, having drive based backup, or a program that'll back up for you on another drive, i.e external.
Another one could be to get a program like Norton Ghost, and every few months, to make a back up of your entire drive, compressed, ready to decompress and load when you need it.