We discussed this topic once and again, but there still exists a necessity to return to it because of new accidents.
It is a simple problem, really, and it is the result of excessive friction occurring between the skin and the shoe. When does it happen? - When the foot slides inside the shoe while landing on the ground ahead of the body, or when the foot slides to the side while pronating or supinating.
There are some additional factors "helping" this process, such as: wet condition inside the shoes and an uneven surface. Blisters also develop in the point of the strongest contact, when the shoes are too tight.
So in order to avoid the development of blisters, we need to choose the proper size of the shoes, with a good smooth surface inside, and no possibility of foot sliding inside the shoe. A pair of nice, tight, water absorbing socks, reducing the friction between the foot and the shoe would help a lot.
And the main thing to remember is to always keep the foot under the hips on the ground, never produce any push off or toe off efforts, and never land on the heel. This will prevent your foot from sliding forward, inside or outside and you'll never have blisters again.