For this achievement, you’ll have to earn Revered standing with all factions available to your side. While Champions of Azeroth and Tortollan Seekers reputation is required for both factions, Horde and Alliance players will have different requirements based on their storylines. You’ll earn reputation with these factions by completing story quests in their respective zones, as well as by doing World Quests. We recommend using an addon such as World Quest List to easily see which World Quests award reputation with which faction.
The Horde will now control most of Kalimdor, and the Alliance most of the Eastern Kingdoms. For a low-level character the quests and storylines won't change, but for high-level players many zones will see changes via phasing. Teldrassil is burned and Undercity is in ruins as the story progresses by phasing. At max level Arathi Highlands and Darkshore are phased to be updated to reflect their status as locations for Warfronts.
Even if you don’t have flying in WoD be sure to get the WoD handy notes. If you have flying simply fly and pick up all the treasures that you can and do bonus objectives. Not every single piece of treasure will be worth it though as some are hidden in caves or are just hard to get. So if you find yourself spending more than a few minutes finding a treasure, just skip it and move on, there is plenty of treasure to go around.
The last farm on this list, actually I was surprised this farm eluded me for so long. Generally speaking gnomergan is a huge confusing instance that takes some getting used to but if your a high value transmog farmer this does not scare you. You can pull the entire instance and get access to a plethora of high value loot such a recipes, world drops, greens and even engineer supplies. Overall this farm is shadowed by the Diremaul farm and Zulfarrak farm, but is an equal change of scenery with a wild card if you get the hot shot pilots gloves OR the mechbuilders overalls worth 400,000g and 60,000g respectively. A pretty cool neat farm that noone really mentioned until now.
The Auction House is always the best option for getting good equipment at a good price. The only items you should be buying from Vendors are basic consumables: food, drinks, arrows, bullets, vials, dyes, etc. Most other things should come from the Auction House, as they are generally cheaper. Keep these tips in mind when buying items off the Auction House:
First of all, the value of transmog is decided by rarity and how they look. Some items like Minenarbeithut der Tiefen or Pendel der Verdammnis (they can drop in Uldaman) are worth millions of gold. They are worth so much, because they have a really small chance to drop. Other items are bought well because they look good. Best example in this case is the Glorious set, its legplates Glorreichen Beinplatte reach a 100.000 Gold value easily.