The publisher already commented on the game’s leveling speed following the launch of the Battle for Azeroth 8.0 pre-patch earlier this month. “Since the pre-patch we’ve made a large number of hotfixes and changes to leveling content, and are continuing to find and fix bugs wherever possible”, Blizzard wrote. “The intention was never to make leveling slower than it was in 7.3.5.”
Professions: This may seem strange for a leveling guide, but the first opportunity you get, pick up both the Mining and Herbalism gathering professions. Not only will this allow you to track many various quest objectives on your map, but you also get a fair amount of experience whenever you gather. I'd put it at around 10% of a quest turn-in per gather. Since most of your wasted time in WoW is travel time, stopping to gather ore or herbs can keep your exp/h rolling as long as you don't go too far out of your way. You should only gather if it's convenient, and on the way to an actual quest objective. Don't make gathering your priority.
As you can see, every profession is represented with these quest givers. What I was alluding too with the scrap bot is if you scrap your gear, you will have the mats required for someone who has this profession to be able to make the required item for you. That or you could trade other players for the items required for these turn ins. You will need the help of other players or a lot of gold in order to complete all 11 of these turn ins. Having a guild here will help a lot with this process.
These two expansions are virtually identical in terms of exp/h. I personally favor Mount Hyjal, and think it's very slightly faster. But if you know Jade Forest well you can just as easily keep up there. Ultimately you'll end up doing both anyway, so it's mostly academic. Every time I've tested Valley of Four Winds or Deepholme, or any other zone in MOP/CATA's level range, they were worse exp/h. You should not even need to complete both zones to ding 91, so it's more important to just pick one and go.
Many people have asked whether we recommend leveling as Enhancement or Elemental. There’s no definitive answer here; it depends entirely on your comfort, your gear options, and if you’re in a group or solo. Enhancement benefits more from Honor Talents in open world leveling, and Elemental has stronger AOE damage for mass pulling. Feel free to experiment with both specs.
Résumé des informations (TL;DR) : Spoil  Terminez toutes les quêtes disponibles, récupérez un maximum de Puissance d'Azerite, faites le Front de Guerre une fois niveau 120 pour récupérer un loot 370 ilvl et accéder aux quêtes, faites le Front de Guerre chaque semaine pour la réputation et l'AP, faites les World Quests pour la Rep/AP/Émisaires, trouvez de l'équipement grâce aux donjons et assurez vous de faire les 9 disponibles en difficulté mythique.

The leveling guides on my site are essentially speed leveling guides.  My leveling guides are the same guides I use myself to speedrun to 60 on new servers to get 60 server first.  I list many occasions where I tell the player to "die on purpose" to go faster.  I tell the player to skip certain quests, because some quests are just not worth the time/XP.  I list tricks and shortcuts to go faster so you can reach level 60 much quicker.  I am still constantly going through them over and over again perfecting the guides to make them faster and easier to follow.  For the most part, the guide can be followed without the need from other player's help, as the whole guide was made from a solo run anyways.  Although I do list quests that can optionally be done if you have a group.

The level cap represents the ultimate goal and culmination of the leveling process, with max-level characters having gained access to all class abilities and talents, and being able to access end-game content and equip the most powerful gear. By providing an equal limit for the progression of all characters, the level cap allows for competitive and balanced gameplay in both PvE and PvP.
- Right to restriction on processing. If there are grounds for restriction on processing, for example if you contest the accuracy of your personal data, it will be stored and processed otherwise only if you consent or to exercise legal claims, or for the protection of rights of another natural or legal person. If we have disclosed the personal data in question to third parties, we will inform them about the restriction on the processing of the personal data, unless it is impossible or involves disproportionate effort to do so. We will inform you before the restriction is lifted.