Alright sosmithing/forging is probably the easiest skill to get up in this entire game. If you have the money to do this then it'll take around an hour.

:!: The total cost for this is in excess of 10,000 gold so just be aware :!:

I found this and it works perfectly. I have 100 smithing/forging and the achievement to show for it

TUT:

Alright so first what you're going to want to do is travel to Whiterun and go to Warmadiens (the weapons shop right by the fast travel location). You're going to want to go in and click the buy/sell option with the shop keeper. Go down and buy out all of the leather, iron ingot, and iron ore. After you do this go outside and go to the left side of the shop outside. There will be a tanning rack where you can use all of your leather on (you get 4 leather strips per leather so it's cheaper than buying leather strips from the shop). So when you have your leather strips go to the smelter and smelt your iron ore into ingot and then go to the forge and proceed to make iron daggers.

Very important: for the best and cheapest results ONLY make iron daggers because it take the least amount of materials to make this.

I actually noticed that in this game every item gives the same amount of experience for smithing no matter what the item is. So making iron daggers is your best option.

So now you have a lot of iron daggers, if you want you can enchant these to make some of your money back but if that's too much effort then just sell them back.
Now you can go to other places to buy your iron while Warmadiens resets their stock (takes 24-48 hours in game time). So you can travel to the skyforge, riverwood, solitude, etc... It just has to be anywhere that has a weapons dealer and a forge. Just repeat the process you first did and make iron daggers all the way to level 100.


You will get around 5-7 actual levels just by doing this and you'll also be able to make armor such as glass, ebony, deadric, and most importantly DRAGON armor. It looks awesome and there's a heavy and light version of the armor. And you also get an achievement which is pretty nice.
Edit: picture of the heavy armor version:

Sorry for not having pictures right now. I'm not at my house currently but hopefully you'll be able to read this and get how to get 100 smithing/forging.

Also, I do take credit for this guide because I found this out on my own and wrote this guide on my own. Sorry if this has already been posted but I currently don't see anything similar to this and it's a pretty useful guide.
If you have any questions just reply here and I'll answer them