Blisters are better prevented than treated, so if you feel a hot spot on your heel, cover it immediately with tape such as Leukosilk and then Leukoplast on top. Some people do this before a hike to prevent the hot spots.
A Vaseline coating on the feet and between the toes prior to a hike also prevents rubbing and blisters, a trick employed by marathon runners for years. Good quality socks provide extra comfort and minimise rubbing. Talcum powder is great after a hike to help the feet recover.
Check out my ‘blister free’ gear review here.