Compeed are indeed a wonderous invention and I tend to use these on my heels once I have blisters.
I've recently started trying to prevent them instead - makes sense - and use zinc oxide tape, which you should be able to buy from a chemist (or a climbing shop - I use it on my hands for climbing.) You can get in lots of different widths, so should be able to cover any area of your foot with the stuff. Once on, cover it with vasaline and then stick on your sock(s) - should help prevent some of the rub.
Micropore can work just as well.