This article is from the Living Barefoot FAQ, by Paul J. Lucas with numerous contributions by others.
Once your feet are in good shape, I would be _very_ surprised if you
ever got a blister from walking barefoot. Blisters are caused by
continual rubbing in the _same_ spot over and over; while walking
barefoot, your soles get rubbed all over and no one "hot-spot"
But, should you "over-do" you barefoot training and get a blister, you
can follow the procedure below.
[_Note:_ I am not an MD and the following does not constitute medical
advice. It is my own personal experience and is what works for me.]
What worked for _me_ when I used to get blisters was to lance the
blister with a sterilized needle and squeeze the fluid out. Leave the
flabby skin on! If the blister is small, it may "reattach"; if not, it
will protect the soft, "virgin" skin under it until it becomes harder.
Then, after a few days if it does not reattach, carefully trim it off
with a small pair of scissors or a nail-cutter in a chopping manner.
After treating a blister, the the best thing to do, believe it or not,
is to walk barefoot more! (You _did_ leave the skin on, right?) Your
body will recognize the "need" for thicker skin and this will help
prompt the skin to reattach.
A blister, if you followed the above procedure, will get to the point
where you don't notice it in under a week. You will still see a
"crater" for up to 3 weeks, though.