Semi new to bit coin, I use bitcoin-qt as my wallet. I do encrypt my wallet files and back them up in multiple locations and email it to myself. My questions is how often should I be backing it up? I have heard every 100 wallet address that you create, but I have also heard of "change addresses" being created without my knowledge. What do you guys do?
The more you send payments the more it should be backed up. If you are mostly getting payments it doesn't matter. Change addresses occur when you are sending. You could always switch to Electrum or Armory and you only have to back up once.