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).
All the things that kept trade goods cheap while the value of gold was falling are no longer true in the new expansion. Most players are working on gearing up their main characters right now, and it will be a while before people earn the levels and reputations on secondary characters to serve the markets for high-end trade goods, so there are fewer crafters competing with each other to serve a community that is swollen with returning players.
Finally: Gearing happens in a pretty linear way for BFA. Once you hit 120, normal dungeons drop 310 and you need 305 item level to start heroics. Heroics drop 325 and I recommend doing Mythic at around 320. Mythic drops 340 and I highly recommend clearing every single mythic dungeon to give you the highest item level going into week 2. On launch, you will have access to 9 Mythic dungeons and there will be 1 dungeon that is gated behind honor bound rep; Siege of Boralus is gated for the Horde and King’s Rest is gated for the Alliance. I am not 100% sure on this, but I do not believe you will be able to obtain enough Honorbound rep to unlock those dungeons with the first week. Either way, its important to get a clear of all 9 dungeons first week to give you the most chances at loot. If PvP is more your thing gear starts at 280 and I am not 100 percent sure how PvP gear works for BFA. I will do more research and fill this in the best I can.
Kael'thas - Alliance Kael'thas - Horde Karazhan - Alliance Karazhan - Horde Kargath - Alliance Kargath - Horde Kazzak - Alliance Kazzak - Horde Kel'Thuzad - Alliance Kel'Thuzad - Horde Khadgar - Alliance Khadgar - Horde Khaz Modan - Alliance Khaz Modan - Horde Khaz'goroth - Alliance Khaz'goroth - Horde Kil'jaeden - Alliance Kil'jaeden - Horde Kilrogg - Alliance Kilrogg - Horde Kirin Tor - Alliance Kirin Tor - Horde Kor'gall - Alliance Kor'gall - Horde Krag'jin - Alliance Krag'jin - Horde Krasus - Alliance Krasus - Horde Kul Tiras - Alliance Kul Tiras - Horde Kult der Verdammten - Al... Kult der Verdammten - Horde
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.
Edit 20 It’s been a week since this post and a lot of people are still reaching out to me with questions which is fine. I have had a few different people reach out to me to help make YouTube videos based off this guide and more info in BFA which I’m more than willing to do. Whoever gets the videos up first I will link them here for you guys to enjoy.