Leveling up Skinning starts by visiting a Skinning Trainer. You can find one by talking to the nearest guard in faction’s big city (like Orgrimmar or Stormwind). They will send you to a Skinning trainer where you can buy a Skinning Knife and pay a few silver to become a level 1 Skinner.
To get started leveling, find any level 1 through 10 beasts to kill and skin. Beasts are monsters with the ‘Beast’ label below their name. They are usually things like bears, wolfs, spiders, dragonkin, whelp, and others. I recommend you head to Maclure’s Vineyard in souther Elwynn Forest where you can farm lots of Light Leather. You can stay here until your Skinning is about level 75. You can also head to the northern edge of Duskwood to skin spiders and collect Light Leather. If you’re Horde, head to the northern area of Silverpine Forest and kill bears and worgs.
At level 75 you can head to Westfall, Darkshore, Loch Modan or Hillsbrad Foothills to skin beasts until level 150
Once you’re at least level 150, head to The Cape of Stranglethorn, right outside the Crystalvein Mine killing and skinning Basilisks. If you’re on the other continent, you can head to the northern area of the Southern Barrens (Hunter’s Hill) to kill raptors. You can farm Medium Leather in either of these places until you’re level 200-250. It really does’t matter when you leave but you have to be at least level 200 to go on to the next area.
At level 200, you can start farming Heavy Leather in Feralas in either of the Yeti caves. One of them is north of ‘Ruins of Isildien’ on the map, and the other is south of ‘Dreamer’s Rest’ on the map. If you’re on the other continent you can head to Dustwallow Marsh and kill dragonkin and whelps all around Stonemaul Ruins. Stick around until at least level 250.
At level 250, you can head to the south eastern part of Un’Goro Crater killing and skinning Ravasaurs around the marshes for Thick Leather. Otherwise, head to Badlands and kill dragonkin, whelps, coyotes and stalkers on the western end of the zone. You can stay here until level 300 or you can go farm Rugged Leather at level 275. Rugged Leather is often the most valuable leather to sell on the auction house besides Savage Leather.
If you’re level 275 you can farm Rugged Leather in the Blasted Lands or Winterspring. In the Blasted Lands, you will find beasts all around the road in the center of the map. In Winterspring you can kill and skin frostsabers and bears in the north. Don’t leave this area until you’re level 300 skinning, you can stay longer if you want to collect more Rugged Leather.
Once you’re level 300 Skinning, you can go to Outlands and kill Hellboars and Ravagers in Hellfire Peninsula. When they no longer give you level ups you can go to Nagrand and skin the beasts all over the zone. Sell the Knothide Leather that you collect in the Outlands for a good profit.
At level 375 you can go to Howling Fjord and kill Shoveltusks near Westguard Keep, do this until you’re level 405 and then head north to Grizzly Hills and kill wolves and bears scattered throughout the zone. Once you’re level 430 you can go to Sholazar Basin and skin just about anything until you are level 450. Sholazar Basin is almost 100% beasts.
To get from level 450 to 525 you should go to the beginning of Kelp’thar Forest and skin serpents and crabs for Savage Leather. At level 470, head to the river banks of Uldum to kill Crocolisks until level 485 when you can finally head to Twilight Highlands and kill any of the beasts in the center of the zone.