With my smithing skill at 100, when I improve weapons, it of course raises the damage and value of whatever I improve. Doing some testing, I found that not only do smithing enchantments raise the damage and value even further, but they also stack with one another. (Tested this using as many max smithing enchants as possible across multiple pieces of armor.)
If you max out your enchantments and use smithing enchantments to improve 100 smithing, you can create laughably overpowered armor.
Alchemy is alchemy. You can create potions and poisons that would in theory improve them even more as you use them, but I don't use potions myself. I'm sure someone else can confirm what they do best.
This is how I understood it, you need an fortify enchanting effects, with it you can boost your enchanting skill, so you can make even more powerful enchants.
Now with an fortify smiting effect you can make smiting gear for an serious boost.
However if you add alchemy into this it start getting weird. make some alchemy gear with fortify alchemy enchant effect,
now make an fortify alchemy potion and drink it, now create some fortify enchanting potions and make a new and better fortify enchanting gear, with this create new alchemy gear, over to the alchemy table and make more powerful potions.
I see no reason to stop here as I get an strong Morrowind feeling out of this even if the cycle is more complicated and involves grand souls.