I read an article years ago in a running magazine that suggested duct tape. It works fabulously. I put it where I get blisters and I don't have any trouble at all, and it doesn't leave a sticky residue on your skin.
I would probably wait till the blister healed though, in the mean time, I would use a band-aid and then possibly put the duct tape over it.
I didn't want to post this, because I fear I look like a crazy person, but it works so well, I just had to.