As always, I will monitor and update this guide as new information comes in. If I've gotten anything glaringly and completely wrong, just tell me with as much data as possible. The idea is to find the fastest possible leveling method, NOT to argue about how good or bad individuals are. If you have hard data, post it! If you have an idea, let the thread know so we can test it!
Level with a pet if you can because it will help keep you safe. If your pet is tanking all of the damage from the enemies you’re fighting, you won’t have to. The other reason is that pets are easier and cheaper to heal than you are. If you don’t have a pet, make sure you know how to use your defensive abilities. You can’t level quickly if you are dying all the time.
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:
Level 65 unlocks Greater Invisibility. This can be used to instantly escape combat with any enemy, or reduce the damage of big hits by 90%. Keep in mind, when using Greater Invisibility, you will drop combat, and lots of enemies will start evading and healing back to full Health, so do not use this on low Health enemies if you would survive the hit.
Meanwhile, in Zandalar, the Horde seeks to earn the trust of King Rastakhan so they can use his legendary Golden Fleet against the Alliance. To this end, they assist Rastakhan and his court in dealing with local threats in Zuldazar, fight maniacal Blood Trolls in Nazmir, and face off with serpentine Old God cultists in Vol'dun. Throughout their journey, the Horde gradually learns about an eldricth being known as G'huun, an artificial Old God accidentally created by the Titans and the patron deity of the Blood Trolls. The Blood Trolls and the Faithless Sethekk seek to free G'huun from his prison of Uldir so they can use him to rule Azeroth, and to this end they resurrect G'huun's champion, the C'thrax Mythrax, to destroy Uldir's seal. Rastakhan's own chief adviser, the prophet Zul, is revealed to be the Blood Trolls' secret leader and launches an armed revolt against Rastakhan. With the Horde champions' help, Rastakhan is able to defeat Zul and his forces, but not before Mythrax destroys Uldir's seal.
As for Battle for Azeroth’s lack of new 120 talents, Hazzikostas explains it as a tough scenario. If the designers come up with three new abilities for rogue or death knights, those classes may not necessarily need three new abilities. Those abilities may be filler, or they may shore up a weakness in the class design and remove counterplay. That being said, Hazzikostas does agree that “it’s possible we’ve gone too far.”
Once you reach 575 you can purchase vendor recipes for the last 25 points. The Blacksmithing recipes are on a vendor in Vale of Eternal Blossoms. You can enter Vale of Eternal Blossoms after completing the questA Celestial Experience (requires level 87). After you completed the quest, you can find Jorunga Stonehoof (Horde) in Shrine of Two Moons and Cullen Hammerbrow (Alliance) in Shrine of Seven Stars.
Buffs. Food/Flasks/Scrolls/Potions/Elixirs are a small, but noticeable, buff to your killing speed and survivability. If you have a max level character that can already supply you with cooking or alchemy, you'll be very well off, because the AH is a cesspool for this. I can't really give you specific foods or potions to look for, since each AH is going to have different supplies. Generally speaking, lower level foods are going to only last 15-20 minutes until you can buy the more powerful versions at 60+. Look for anything that adds versatility or your primary stat, and buy stacks for each level range(1-60/70/80/90/100).
Now that you have the addons and the websites needed for success, you are ready to make auction toons. You will want two auction toons, one on the same faction as your main toon and one on the opposite faction. Do not use your main toon to make the auctions that get you gold! This is one of the greatest mistakes you can make because after a while, people will get annoyed with your prices and selling quantities and begin to blacklist you from groups and some will even boycott your products. Do not risk this happening to you, but rather, create an orc for horde and human for alliance and get them outside the nearest auction houses in Orgrimmar and Stormwind respectively. (As a personal preference, I tend to avoid names with bank, mart, or sell in the name because when negotiating outside of the auction house, you seem less personal). All the addons we downloaded should be enabled for these characters as well.
You can earn a decent amount of XP by doing Herbalism or mining. Any zone works but I prefer Sholazar Basin as a lot of the mobs are not aggressive and the mobs are spread out so you will find a lot of herbs and ore that you don’t have to fight for. It is possible to make about a level every hour by doing this, or a level every 30-40 minutes with rest XP.