I use Sportslick: http://www.amazon.com/dp/B0007OC0A2/?tag=casaivar02-20
I put it between my toes, on top and bottom of my toes, along the side of my foot, and on my heel. The 3.8 oz. tube lasts for a camino, so I would say I use a medium amount per application. It is mostly in my liner socks...