Skinning is a “no brains” way to easily make some extra gold and is the best way to support the Leatherworking profession. The easiest way to level skinning to 300 is to do it while you are leveling your character. You will likely hit 300 skinning long before hitting level 60.
Here are some routes for leveling the Skinning profession. Just run around and kill skinnable creatures (beasts, whelps, dragons, etc.)
1-50 (Alliance) – Elwynn Forest
Tips: Try to avoid the Murloc and Kobold camps.
1-50 (Horde) – Durotar
Tips: Just run around and kill boars/scorpions. There are so many you’ll hit 50 skill before you kill them all.
50-100 (Alliance) – Westfall
Tips: Avoid the farms themselves but focus on the area between the farms and the area between the road and the river on the east coast.
50-100 (Horde) – The Barrens
Tips: There are so many skinnable creatures around/inside the Wailing Caverns, this is the only place you’ll need to go. Alternatively, just scour the zone: beasts galore!
100-150 – Hillsbrad Foothills
Tips: There are so many mobs to skin in this zone you can honestly just wander aimlessly and basically never run out of mobs. Alternate spots (blue): Yeti Cave or (green): Turtles in the river.
150-200 – Alterac Mountains
Tips: Focus on the yetis and mountain lions.
200-250 – The Hinterlands
Tips: Make tight loops and avoid the troll ruins. Alternate route (blue): Turtles on the beach.
250-300 – Un’Goro Crater
Tips: Avoid the Silithid tunnels (south center) and the Fire elementals at Fire Plume Ridge. Alternate routes (blue): Pterrordaxes around the East and West Pylons.