Leveling Blacksmithing is cheapest if you’re also a miner, but if speed’s what you want and money’s no object, just buy all your materials on the auction house and get your blacksmithing leveling done in an hour or two. Blacksmithing offers you bonus gem sockets and is currently making a nice profit from Eternal Belt Buckles.
Ackis Recipe List, scans your trade skills and provide information on how to obtain missing recipes, patterns, enchants, plans, and schematics.
Blacksmithing Leveling Guide 525-600
Blacksmithing Leveling Guide 1-525
If you need more detailed information check out my favorite guides here.