Running

One on my heel, which must've been just above my running sock, and one on the, er, side of the ball of my foot, if that makes sense. The ball one is manageable but the heel one is a bit of a mess. Annoying as I guess it makes my running socks a bit useless with those shoes.

Try different socks. Everyone has different preferences and different experiences.

I wear "1,000 Mile" socks - double skinned, either the socklet or full sock version. These seem to prevent any blisters when I'm wearing Brooks Glycerins or Brooks Defyance, but are useless with my Inov8s.

You'll need to experiment, I guess.

In addition to Hats's suggestions, urea is supposed to help toughen skin. So you need to pee on your feet.