This can be a time consuming achievement, but very simple to complete. Here's the list of candy buckets you must visit:

Alliance

1. Blade's Edge Mountains, Evergrove
2. Blade's Edge Mountains, Sylvanaar
3. Blade's Edge Mountains, Toshley's Station
4. Hellfire Peninsula, Honor Hold
5. Hellfire Peninsula, Temple of Telhamat
6. Nagrand, Telaar
7. Netherstorm, Area 52
8. Netherstorm, The Stormspire
9. Shadowmoon Valley, Aldor or Scryer Inn
10. Shadowmoon Valley, Wildhammer Stronghold
11. Shattrath City
12. Terokkar Forest, Allerian Stronghold
13. Zangarmarsh, Cenarion Refuge
14. Zangarmarsh, Orebor Harborage
15. Zangarmarsh, Telredor

One way to go about this is to start from Shattrath. If you follow this route, visit the following cities in this order:

1. Shattrath City
2. Terokkar Forest, Allerian Stronghold
3. Shadowmoon Valley, Aldor or Scryer Inn
4. Shadowmoon Valley, Wildhammer Stronghold
5. Nagrand, Telaar
6. Zangarmarsh, Telredor
7. Zangarmarsh, Cenarion Refuge
8. Zangarmarsh, Orebor Harborage
9. Blade's Edge Mountains, Sylvanaar
10. Blade's Edge Mountains, Toshley's Station
11. Blade's Edge Mountains, Evergrove
12. Netherstorm, Area 52
13. Netherstorm, The Stormspire
14. Hellfire Peninsula, Temple of Telhamat
15. Hellfire Peninsula, Honor Hold

Horde

1. Blade's Edge Mountains, Evergrove
2. Blade's Edge Mountains, Mok'Nathal Village
3. Blade's Edge Mountains, Thunderlord Stronghold
4. Hellfire Peninsula, Falcon Watch
5. Hellfire Peninsula, Thrallmar
6. Nagrand, Garadar
7. Netherstorm, Area 52
8. Netherstorm, The Stormspire
9. Shadowmoon Valley, Aldor or Scryer Inn
10. Shadowmoon Valley, Shadowmoon Village
11. Shattrath City
12. Terokkar Forest, Stonebreaker Hold
13. Zangarmarsh, Cenarion Refuge
14. Zangarmarsh, Zabra'jin

One way to go about this is to start from Shattrath. If you follow this route, visit the following cities in this order:

1. Shattrath City
2. Terokkar Forest, Stonebreaker Hold
3. Shadowmoon Valley, Shadowmoon Village
4. Shadowmoon Valley, Aldor or Scryer Inn
5. Nagrand, Garadar
6. Zangarmarsh, Zabra'jin
7. Zangarmarsh, Cenarion Refuge
8. Blade's Edge Mountains, Evergrove
9. Blade's Edge Mountains, Thunderlord Stronghold
10. Blade's Edge Mountains, Mok'Nathal Village
11. Netherstorm, Area 52
12. Netherstorm, The Stormspire
13. Hellfire Peninsula, Thrallmar
14. Hellfire Peninsula, Falcon Watch