What the achievement asks
Finish Roko the Wandering Merchant's five quest storyline in Tiragarde Sound. Five points, account-wide, Alliance only, and it pays a decoration: the Tiragarde Treasure Chest.
The quests themselves are short. Getting Roko to offer you the first one is the part that stops people.
The five quests
They run one into the next, so once the first appears the rest follow on their own.
Finding the right Roko
There are several copies of Roko around Tiragarde Sound, and only this one offers the chain. People conclude they are missing a prerequisite when they are simply standing in front of the wrong tortollan.
He is a few steps from Flynn Fairwind, by the bridge.
Getting there from nothing
If you have never quested in Tiragarde Sound, the chain is gated behind a good chunk of the zone story. The route, from a standing start:
- Take Battle for Azeroth: Tides of War from the Hero's Herald in Stormwind.
- If the War Council does not appear where the quest points, pick up the first quest from Magni Bronzebeard, in the room to the right of Anduin's throne, and complete it. The council then shows up.
- Follow the chain until Jaina takes you to Tiragarde Sound, where you pick up Get Your Bearings.
- Quest until you are introduced to Cyrus Crestfall, then take his quests until Flynn Fairwind offers you one. He is leaning against a wall in the same room.
- Follow Flynn to The Ashvane Trading Company, take the ferry, and clear Freehold.
- Turn in Papers, Please and The Irontide Crew.
Roko then offers Aged to Perfection, and the five quests are yours.
If you are already partway in, going straight to Cyrus Crestfall in Boralus and following his quest line rejoins the route at Flynn Fairwind.
While you are there
Flynn also offers the chain that leads to Rodrigo's Revenge, which is how you get the parrot for Bless the Rains Down in Freehold. Do that achievement before turning the quest in: the two are in the same corner of the map and the trip is otherwise wasted.