Skin everything with four legs.
Skinning allows you to take a skinning knife to the various beasts of World of Warcraft and remove their pelts and skins. You can then use these primarily in the leatherworking profession, although some other recipes scattered in the other crafting professions also make use of the occasional skinning item. It’s one of the tougher gathering professions to level, as you actually have to kill things in order to raise it. If you take skinning, you should try to take as many beast-killing quests as you can, and you should be able to ensure that your skinning keeps pace with your character level without needing to take special pains to fight beasts forever.
One trick to get you skinning faster that many players simply never learn about is to hold shift when you right click to loot. This activates “quick loot,” making you loot everything without needing to click it manually. You can do this with all objects in the game, and in your skinning as well. Added up over the thousands of beasts you will kill and skin, it saves you hours of time, adding greatly to your efficiency. Monsters require five points of skinning per level of the creature in order to skin. You can often skin beasts that have been killed by other players as well, so sometimes it pays to hang around when someone else is killing a lot of beasts even if you’re not grouped with them. Save your leather scraps, as leatherworkers can turn them into ordinary pieces of leather.
Dragon scales and other special pieces can be skinned off of special monsters, which can be used for particular leatherworking items. While skinning isn’t quite as lucrative as mining or herbalism - as only one profession really uses the materials significantly - it’s a great companion profession to leatherworking, or even as a compliment to an existing gathering profession. It helps to play a class that can solo lots of monsters very quickly, or skinning will really just give you a headache while you’re leveling. A protection warrior with skinning will find themselves quite bored unless they have excellent gear, for example. When the Wrath of the Lich King comes out, skinners will all receive the permanent Master of Anatomy buff, which increases their critical strike rating between 3 and 25 depending on your skinning level, which is equivalent to 0.54% at level 80. It’s not a bad boost, but it’s not really sufficient to make someone choose skinning over any other profession only for that buff.