I'm currently working on 1-400 on 3 of my 4 DKs. (My 4th is already maxed). I'm only worried about getting to 400 so I can get the socket bracer and socket gloves for the extra gem slots. I've currently got 2 of the 3 to 300, and 1 at 200. I've not gotten into the BC mats so I don't know any of the tricks, however there are a few helpful things to know from 200-300. As with anything, your mileage may vary, but hope this helps someone, would have saved me some relogging and headache.

Following this guide: http://www.wow-professions.com/wowgu...ing-guide.html

Here's the list of materials needed to get to 400 on each toon..

133 Rough Stone
190 Copper Bar
70 Coarse Stones
125 Bronze Bar
7 Silver Bar
105 Heavy Stone
5 Gold Bar
230 Iron Bar
35 Green Dye
50 Steel Bar
75 Solid Stone
380 Mithril Bar
160 Mageweave Cloth
20 Dense Stone
420 Thorium Bar
10 Star Ruby
122 Fel Iron Bar
7 Netherweave Cloth
85 Adamantite Bar
280 Cobalt Bar
25 Saronite Bar
Tips / Tricks:
For these 2 items I quote you more solid stone since I had to get extras on both toons because the recipe goes green before you hit the target skill.
200 - 205 5 x [Solid Sharpening Stone] - 5 Solid Stone
205 - 210 15 x [Solid Grinding Stone] - 60 Solid Stone
For this part I found it easier to make the Mithril Scale Pants. However it requires more mats (that I accounted for above)

225 - 235 10 x [Mithril Scale Bracers] - 80 Mithril Bar
This recipe is sold by these NPCs. There is around 30 minutes respawn rate for the recipe, this means you have to wait a bit if someone bought it before you. Make [Mithril Scale Pants] if you do not want to wait for the recipe to respawn or check the Auction House and look for [Plans: Heavy Mithril Pants]
For 275-290 I didn't want to deal with Arcanite so I just made the 15 x [Imperial Plate Bracers] 180 Thorium Bar
275 - 290
Between 275-280, you can make [Arcanite Rods] and sell them at the Auction House. This way you will need 55 less [Thorium Bars]. The recipe is yellow, so it really depends on your luck, maybe you will only need to make 5 maybe 10.

One [Arcanite Rod] costs around 18 gold to make if you buy the [Arcane Crystals] and find any Alchemist who transmute them into [Arcanite Bars]. The 55 [Thorium Bars] cost around 140 gold usually, but this way if you have to make only 5 [Arcanite Rod], you will end up around 90 gold spent, and you can also sell them for profit. I can usually sell them for around 70-80 gold, but you have to be patient because the demand for them isn't that big.

Anyway this is a great way if you want to reduce the gold spent while you level your Blacksmithing, but if you want to level the profession faster and you don't really feel you are lucky or you are not really into selling things at the Auction House, you should just make the Bracers mentioned below.

15 x [Imperial Plate Bracers] 180 Thorium Bar
For 290-300: I made the Thorium Helm because the Star Rubies were much cheaper than Rugged leather, YMMV
290 - 300
Choose one from the recipes listed below. They both requires 12 Thorium Bar for each craft, the only difference between them is that you need 1 Star Ruby for the Helm and 8 Rugged Leather for the Boots.
10 x [Thorium Boots] - 120 Thorium Bar, 80 Rugged Leather

or

10 x [Thorium Helm] - 120 Thorium Bar, 10 Star Ruby