This WoW Leatherworking guide will show you the fastest and cheapest way how to level your Leatherworking skill up from 1 to 600. Updated for WoW patch 5.4
Leatherworking is the best combined with Skinning, it's not required to have skinning, but it's strongly recommended. Check out the Skinning Leveling Guide if you want to level Skinning. You can also buy the materials at the Auction House, but then make sure you have enough gold.
If you are low on gold, I recommend you to try this Gold Making Guide, it can help you to make loads of gold.
If you are still leveling your character or you just started a new alt, I recommend you to use a leveling guide. You can level your character to level 90 in 7 days with this guide.