You need:
100 Smithing
100 Enchanting
100 Alchemy
Perks in Smithing up to Dragon Smithing(Going up the Left side gets you there faster)
Perks in Enchanting:
Realistically you only need to max out Enchanter(first Perk, 5 ranks)
Perks in Alchemy:
Alchemist(5/5), Physician, Benefactor
You're also going to need several sets of gear you dont care about, have unlocked the fortify alchemy and fortify smithing enchantments, and have ingredients for fortify enchanting potions and fortify smithing potions.
You're going to want to make a fortify enchanting potion(or a few of them)
Then go to an enchanter and drink the potion. Then enchant a set of fortify alchemy gear(head, gloves, ring, necklace if I remember right)
Then, wearing your new gear, head to the alchemy station and make another fortify enchanting potion.(It will be a higher percentage than the previous one)
Keep chaining this together until the percentages stop getting higher.(There is a cap)
These numbers can get even higher if you are a vampire and you get the necromage perk in restoration(not a glitch or exploit, game mechanics)
These numbers can get even higher if you have the Dragonborn DLC and you get and wear Azhidal's armor to get the Azhidal's Genius perk which grants a boost to enchanting(wear the armor while using the enchanter)
After getting the best fortify alchemy gear you can get, make another set of fortify enchanting potions and a set of fortify smithing potions.
GO to the enchanter, drink the fortify enchanting potion(s) and make a set of fortify smithing gear(Body, Gloves, Necklace, Ring if I remember correctly.).
Finally go to the forge and DO NOT DRINK THE POTION YET.
Make whatever weapon you want out of dragon bone(you have dragon bones and scales right?). For the highest damage, make a warhammer.
NOW, drink the potion and make sure you are wearing your fortify smithing gear. Temper your weapon at the grindstone and it will be at maximum damage.
To get an even higher damage: max out the appropriate weapon skill(2-handed for a warhammer) and wear the appropriate maxed out fortify weapon skill gear(you know how to make maxed out enchantments by now).
Now enjoy crushing everything in the game,