Wailing Caverns is the first dungeon many World of Warcraft Classic players encounter, especially if they're on the side of the Horde that divides factions. You can get much wow classic gold and items while completing these quests.

While Alliance players will likely use the Deadmines as their first dungeon, Horde players will have relatively early access to Wailing Caverns, as it's located in the middle of the Barrens and is one of the Horde's earliest leveling areas.

Wailing Caverns is a dungeon best experienced around level 15 to 20, though we recommend a higher level, as many of the enemies in the instance can deal quite a blow if you're lower. Also, it's worth doing the Wailing Caverns around level 19, as many of the quests in the dungeon are impossible to complete by any measure of difficulty until that level.

If you're around level 19, 20, or 21, you'll be in the "sweet spot" of all the Wailing Caverns quests, of which there are 5 quests to choose from before entering the dungeon.

All the Wailing Caverns quests in World of Warcraft Classic and where to get them
Where can the task objective be obtained?
Mutant Hide Collect 20 Mutant Hide Nalpak, above the Wailing Caverns entrance
Mutant Destruction Kill seven Mutant Marauders, seven Mutant Vipers, seven Mutant Shamblers, and seven Mutant Dreadfangs. Ebru, above the Wailing Caverns entrance
Smart Drink Collect six Wailing Essences Maybok Mizzyrix, Ratched (requires "Raptor Horns" as a prerequisite)
Snakebloom (Horde Only) Collect 10 Snakebloom Apothecary Zama, Thunder Bluff
Fang Leader (Horde only) Defeat (and loot) Lord Cobran, Lady Anacondra, Lord Pithas and Serpent Lord Nala Wildmane, Thunder Bluff
Another quest, "Glowing Shards," can only be started inside the Wailing Caverns, so you don't have to worry about it showing up in your journal when entering the dungeon.

This quest is triggered after looting the Glowing Shard of the Wailing Caverns final boss, Mutanas the Devourer.