If i start on a new realms, I am farming a lot of transmog from classic and Burning Crusade Dungeons and Raids. In the beginning, i start to post them if they have at least a DBRegionMarketAvg (Average value of an item on all EU realms of the last 14 days) of 500 Gold. All the other items get vendored. The time you hit a stock of 1000 Items, my value treshold raises to around 2.500 Gold. All the items below that value get vendored aswell. Newly farmed items that are above these treshold will be listed. Why? If I start over somewhere, I want to get a certain amount of gold quickly. Cheap items are great for that. Later on, to save time, Quality is better than quantity. As mentioned above, re-posting the items on the auction house takes quite a bit of time. At this point, I can recommend you the TradeSkillMaster AddOn, it makes your auction house work really a hell of a lot easier.
Additional information for residents of Quebec only: The regular annual rate for persons applying for the Triangle credit card is 22.99% for cash transactions and related fees and 19.99% for all other charges. Some applicants may receive a higher or lower regular annual rate depending on a credit evaluation. The minimum payment is the sum of (a) interest and fees shown on your statement, (b) the greater of any amount past due or any balance over your credit limit, (c) the amount of any equal payments plan instalments then due, and (d) $10. Balances under $10 are due in full. For residents of Quebec, the period between the statement date and the due date for payment is 26 days. The billing period covered by each statement can be from 28-33 days. The Triangle Mastercard does not have an annual fee. Examples of borrowing costs (rounded to the nearest cent) assuming that all charges are purchases bearing interest at the regular annual rate of 19.99%, a 30 day month, no charges made on special payment plans and no other fees, additional payments or other changes are:
The most simple thing is TradeSkillMaster. This AddOn shows you quite an amount of information in the items tooltip. In my opinion, DBRegionMarketAvg the best source. It tells me the price, an item was posted on all EU realms in the last 14 days. Why not DBMarket? DBMarket only shows you the items value from your server in the last 14 days. This value often gets manipulated. Some people start to post an item with a 500g value for 500.000 Gold on the auction house for several weaks. As a consequence, DBMarket is rising towards 500.000 Gold.  If you use DBMarket with 100% and post your item for 500.000 Gold, nobody will buy it.
Your server population may determine how much profit you can make. Lower population servers generally have lower prices in the AH as there is less demand, but rare items or recipes can really make a profit as they are harder to come by. Higher population servers have a higher demand. However, they are more likely to have a flooded market, which makes items hard to sell, especially in the case of low-level gathering professions.
This guide covers many of the ins and outs of both making money, and spending it wisely. Many players have "secret" strategies for making money that they wouldn't want to put in a public info site, since it gives them their edge in the marketplace. If you can gain the trust of a successful WoW tycoon, you should ask them some of their techniques. However, this guide covers many of the more common strategies.
5% was admittedly an exaggeration, just felt that low. I'd say it was probably closer to the 30-40% range. It was Artifacts of the Blacksilt, spent a good 10-15 minutes killing Blacksilt Seers to get two damn idols to drop. A quest that had me killing Elder Brown Bears for bear flanks also took quite a while, though that was less due to drop rate and more due to how spread out they were.
Azerite equipment is currently balanced around being able to unlock the outermost, earliest tier of power immediately upon acquisition, while delaying further advancement until the Heart has been further empowered. For example, the first piece of Azerite equipment, gained shortly after the Heart itself, is fully empowered once the Heart of Azeroth has reached level 3. A character at 120 (the maximum for the expansion) may find a piece whose first tier requires the Heart to have grown to level 12 or greater.
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.
Now that you have these addons, it is time to set them up properly to be used as effectively as possible. With the first addon listed, Auctionator, you will get three additional tabs when you open up the auction house: buy, sell, and more. Buy and sell are easy to follow and read, the primary reason why this addon is the top choice and listed as number 1. You can easily set how much to buy or sell, ranging from 1 individual object to stacks of the same good. The most important way to search is by price per individual item. This will avoid both overpaying and underselling, since you can see what one item in a stack is worth compared to what it is worth when being sold on its own. The "more" feature provides an easy-to-follow window of all your auctions up and the details associated with your auction, such as price and time left, in a nice color coded fashion. Without this addon, you will be severely crippled compared to anyone using this efficiently. If you are afraid of addons for security reasons, the rest can be ignored as long as you have Auctionator!

It’s a good thing that the previous expansion, Legion, was the best in the game’s history because Battle for Azeroth is coasting on its success. The major class redesigns that happened then remain in effect (though some are a little worse, and some a little better), and the combination of World Quests and Mythic+ dungeons means there’s always something to do, no matter your skill level or how long you can play.

101+ At this point you'll start taking a penalty on quest/bonus objective experience for every level past 100. Treasures, however, remain worth their full value all the way through level 105, at which point they'll be worth something like 15% less, and then another 15% more when you ding 106. I recommend that you stop questing/gathering entirely, and collect all the treasures you can stomach, only avoiding any annoying to reach ones inside caves or behind elites/rares(where scaling does bizarro things).
Guild Banners. The Banner of Cooperation and Battle Standard of Coordination will increase the experience from kills. They both have a 10 minute cooldown, but when you use one, the other is only locked out for 2 minutes. I was very bad about using these, so it might be worth using a macro to drop them on your first attack against an enemy. Keep in mind you must have reputation with your guild before being able to buy these, so new character may have a bit of a wait before picking them up.
At 98 you have the option to drop what you're doing and return to your capitol city to start the quest for your Legion Artifact weapon. However, I do not believe this is necessary to do right away unless you're struggling with kill speed in your current gear. I would recommend waiting for a natural pause, such as hearthing to repair and clear your bags. From 100 to 107 you won't even really fight mobs that often; only just enough to clear the way to any treasure you need to pick up.
Some quests in my guide are marked as "SKIP" and colored in red.  These quests are simply either too hard to solo or not worth the XP/time and are skipped.  My guide will only list SKIPPED quests if the quest is a direct follow up after completing a quest, not one that you have to click the NPC again to get it.  If you hover over the skipped quests, it will give info on why it is skipped in the guide (unless that info is already listed directly in the guide text).
Before anyone asks - yes there are archived copies of old addon versions both on our github repository and on several of the addon sites we use, and these will continue to be available after Cataclysm comes out, so you'll be able to get those old files if you really want them. I'm not going to bother making these more easily accessible unless you give me a very good reason. "I'm on a private server and I need them since we didn't upgrade to Cataclysm" is a BAD reason - and it's illegal.
Instead, go to Timeless Isle and take the portal to Gorgrond. From there, fly to your respective faction starting zone(Frostfire Ridge or SMV), go to your garrison, and do the quests to unlock your garrison(A short quest chain beginning down near the water where you'd otherwise start after the Dark Portal scenario). For now DO NOT collect any more treasures than absolutely needed to buy 2 experience potions! Treasures continue to be worth superior exp/h all the way to level 104!!! You don't want to begin collecting them until lvl 100 or later.
You earn a large rested experience bonus when you log out in this rest areas. This gives you a massive 200-percent bonus to experience gain from most actions (though experience from quests isn’t included). The amount of rested experience you earn increases the longer you’re logged off, and your experience bar will be blue (instead of purple) while you have the bonus.
Potions serve more utilitarian purposes, and it's up to you to decide whether to make use of them. The most common is the Swiftness Potion, which can provide you a handy boost in speed while going after annoying quest objectives indoors. These are generally MASSIVELY overpriced, because people know how useful they are. I opted not to spend the gold since Warriors are already fairly mobile, but slower classes may benefit greatly from these. 

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.