Gold Dust Exchange is one of the easiest quests in WoW Classic. All you need is to find 10 pieces of Gold dust which is dropped from pretty much any monster in Elwynn Forest. The drop chance isn’t too high and you will have to grind a little. The easiest way to complete it is just to take it and start doing other quests in this area.
It’s great if you also have The Fargodeep Mine quest and Kobold Candles quest. These 3 quests are great to complete together.

Skeletal Shadowcaster is an NPC that drops very nice loot like Silk Cloth, Mageweave Cloth, Strong Iron Lockbox, Citrine and so on. I like this NPC because of lockboxes. The chance of looting a lockbox is about 1%. It’s not high but anyway you will be receiving the lockboxes sometimes.

You can find this NPC in Razorfen Downs. It’s summoned by Skeletal Summoner. So attack the Skeletal Summoner in order to see Skeletal Shadowcaster.

Retherokk the Berserker is a rather tough guy. In the beginning, he fights like a normal NPC but later on after losing about a half of HP he goes into Berserker mode and starts to hit with heavy attacks. If you are lower than 44th level you may experience problems with this enemy.