Fortify Smithing is an effect and enchantment which increases the Smithing skill. It is found in various items and can also be applied to others.
The following alchemical ingredients can be used to create potions of Smithing:
Potion effects do not stack when used, so drinking more than one potion at a time will only extend the duration of the effect rather than increase the potency.
All apparel which contains the word "Smithing" in the name. For a complete list, see Smithing.
Fortify Smithing can be added to clothing, body armour, handwear, necklaces and rings. Headgear and footwear cannot be enchanted though.
Enchantments appear to stack when items are worn, so it's possible to get four boosts to Smithing when wearing a full set.