Just thought I'd put this up here for anyone wondering how to level up quickly on smithing, especially in those annoying high levels. Using this method, I levelled up from 55 to 72 with about two hours work.

First of all, make sure you have a lot of space in your inventory. I had approx. 110/445. (Bring strength potions)

Find the nearest Dwarven Ruin (I used Markarth - Nchuand Zel or something).

Clear the place out completely, sweep every part of the ruin, picking up 'Bent Dwemer scrap metal', 'Large Dwemer plate' and 'Small Dwemer Plate'. These weigh 2 and each produce 3 Dwarven ingots when smelted. 

When you've collected as many of these as possible, leave and smelt them into ingots - if you can't find any more and have space spare, then start taking 'Dwemer decorative struts'.

After smelting these, I spent a good 15 minutes chopping wood and began to forge Dwarven arrows. I came out with around 5000 arrows (worth 4g each), and my level shot up. Repeating this technique with each ruin; dedicating an hour or two to each ruin should get your smithing to 100 in no time.