This guide is for the trading items quest of TWW. It takes place after Link rescues one of the girls from the Forsaken Fortress. From it, you get cool statues and a piece of heart.
On Windfall Island (D2), Zunari, the man who sold you his sail, tells you business is slow. He then asks you to go around and look for Wandering Merchants (Gorons in Discise) to go trade with them for exciting new stuff. If you agree to help, you get the Town Flower, the first of many trading items. For now on, merchants are on Mother and Child Isles (on the outside so don't warp directly), Bomb Island, and Greatfish Isle. First, warp to Greatfish and sail north to M&C Isles to find the first Goron. Show him your Flower and you get the Sea Flower and an oath to send them to Zunari.
The next stop is Greatfish Isle. Warp there and go to the raft where the Goron is. Show him your flower and you get an oath, the product sent to Zunari, and the Exotic Flower. Next, warp to Forest Haven and sail north one box to reach Bomb Island. Find the Goron and trade your flower for the Sickle Moon, and it's sent to Zunari. Now, if you warp to Windfall, you get the MAGIC ARMOR, it makes you invinsible to all attacks for using your magic very fast. You can stop now and just get the armor, or you can read on and get the piece of heart.
Here's the fastest way to get the heart:
1. Greatfish Isle: Warp there and trade the Sickle for Fountain Idol.
2. M&C Isles: Sail north from Greatfish and trade Idol for Big Sale Flag.
3. Greatfish: Warp there and trade Sale Flag for Hero's Flag. Then immediately trade Hero's flag back for Postman Statue.
4. M&C: Sail north from Greatfish and trade Postman for Shop Guru Statue.
5. Greatfish: Warp there to trade Guru for piece of heart.