The Boots of the Vampire, from the dark cave north of Ars Magicana, are potentially the best footwear in the game.
I also didn't use charms, except one. I saved them up until I had better equipment to use them on, but by then I didn't really need the extra bonus. As for using them, see;
Enchanting items - step by step or
Enchanting weapons/armour/items 
