Picking up herbalism and mining is the best professions to have while leveling. Not only will you earn gold as you level, but you will also get extra XP. At level 20 you will get over 500 XP for picking up a ore or a herb while killing a mob only gives a little over 100 XP. Don’t go out of your way to pick herbs if you are trying to level quickly, but pick the ones that are on your way. Leveling from 110 to 120 can be done pretty quickly just by doing this. There are a few items that will help you if you decide to use professions while leveling:
Love the addon, however I'm having a problem. Anytime I try to do specific actions (change my personal notes in guild window, use quest items [i.e.. using the shears from objective tracker to collect goat fur, or any other quest item used from objective tracker], etc.) I keep getting an error that the interface action was blocked by DugiUI. My only options are to cancel and not preform that function, or to disable and reload UI. Any suggestions? Thanks!

How is this better than the in-game quest helper thingie? While that shows you the destination of your quests it doesn’t show you the best order in which to take them, which to skip, and when to move on (such as when you’ve out leveled the area.) .  Zygor’s show you the optimum path to take to complete the most quests in the least time, which will save you lots of time over the quest helper.

Starting off at some mid level? Come into the guide from any level, scroll through, find and click the level you want to start with, and the guide will take it from there. Zygor suggests starting the guide a level or two before your level. This is to allow you to work you way into the local quest chains. Just skip the chains for quests you didn’t pick up along the way, or the quests that you already did.

Dugi’s leveling guide is the leveling addon I’ve always used to level as fast as possible. It will show you where to go and what to do in-game, speeding up the leveling process. This is optional though, as the game already does a pretty good job at showing you where to go at all times. The addon does, however, come with a couple of other nice features and perks.

The guide should advance to the point where you are in the zone's progression. There are a few steps that can-not autocomplete and they should (hopefully) have comments to the effect of -- you need to manually check this step off. -- For some reason you have to click these steps off 2-3 times to work. (the first time will move the tom-tom arrow, the 2nd time unchecks it and the 3rd click advances the guide).
I liked the little discount for the weekend special. I was used to buying other expansions that included a 30 game time card, this did not. However I was prompted to spend gold I had build up and saved, previously playing the game, and it cost me 117000 gold deducted from my combined characters on my old main server. Big download, so I had to wait to play it until the next morning. Gameplay is different, I was used to the old talent point system, alas I had 10 lvl 100 characters, max level garrisons and shipyard. I did the only thing thinkable without having to take time to vendor unusable items that I thought had meaning. Created the new class. Tutorial started at 98, to get you to 100 with a slow intro back into the game. Auction house prices are pretty high with how long this game has been around. I hope to play more soon, but not like the hardcore grind years past. All I know is I am spending remaining gold saved on biggest affordable bags, and whatever flight trainings to keep me moving fast. Game looks good, no lag, I already enjoy the storyline again.

Anyway, however you choose to get to the addon's menu, choose guide list and then pick the zone you want to quest in. There are some zones that will autoselect based on quests in your log, but not all guides or all quests are set up that way. (If you don't want to switch to a guide that auto-pops up choose "not now" or "never") As you can see in the screenshot, there are various categories of guides. Most max level content (such as Argus) is found in Achievements rather than leveling.

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.
These meats are usually really cheap, so I recommend to switch to these dishes at 50, but if they are expensive on your realm, then it's better to make more [Rank 2 - Kul Tiramisu] up to around 75. As a general rule, if 1 Aromatic Fish Oil cost around the same as these meats, then you should make Kul Tiramisu because even if you have to craft 2-3 for a skill point, you would still only need 4-6 Fish Oil, instead of the 10 meats.
To give you some perspective I leveled both a LF Ret Paladin and BE Rogue (so one started from level 20 and the other from level 1). I focused on getting the achievements I was missing for the Loremaster, so not the most efficient route by any means. I was using full enchanted heirlooms (minus the ring) and the WoW-Pro addon though, as well as having War Mode turned on all the way.
Love the addon, however I'm having a problem. Anytime I try to do specific actions (change my personal notes in guild window, use quest items [i.e.. using the shears from objective tracker to collect goat fur, or any other quest item used from objective tracker], etc.) I keep getting an error that the interface action was blocked by DugiUI. My only options are to cancel and not preform that function, or to disable and reload UI. Any suggestions? Thanks!
Who is Joana?  Joana, (AKA Mancow, or FuriousPaul) speedran 1-60 vanilla WoW from 2005 - 2007.  I have been server first to level 60 seven times in a row, along with winning Blizzard's "First to level 50" contest they held back in 2006.  I also have the fastest time through original vanilla 1-60 WoW in 4 days 20 hours. I have produced a very useful 1-60 horde speed leveling guide along with a 1-60 speedrun video.
Let’s start with the basics. At its core, World of Warcraft is a saga that centers on two warring factions: the aforementioned Horde and Alliance. They’ve been fighting each other since the days of MS-DOS, locked a never-ending war—save for those rare moments where they attempt to team up to counter a greater threat—that has taken them across continents, into space, and through time.

Do quests and complete the story of your first chosen area before returning to your capital to scrap all of the equipment items you acquired. You should be around Level 113 by the time you complete your first area. Before selecting your second zone, head to your faction hub ship to acquire your introductory quests to the mission table and your champions. Complete this introduction and then pick up the quest to establish your first foothold in enemy territory.
A dungeon should take about half an hour to 45 minutes, that is reasonable. What did we do to Maw of Souls because it was by far the fastest dungeon to spam run for AP? Nerfed its yield. Same happened to dungeons. Except instead of nerfing the XP, they adjusted the clear speed to justify the experience a bit more. Is it perfect? Nah, a lot of dungeons aren't even that long with updates. At most a clear takes 5 mins more.
Each of those modes existed long before this latest expansion; raiding is a basic concept in MMOs, and Mythic+ was added in World of Warcraft’s last expansion. The problems with Battle for Azeroth’s endgame come from the systems it adds, which most often artificially gate progress where most of the fun can be found. If raids and Mythic+ are the carrot, we’re about to talk about the stick.

Through out the game, the quest log will be capped to 20 many times.  The guide makes use of maximizing the total amount of quests you can accept at once.  Because of this it is important to follow the guide exactly and only accept quests if the guide tells you to so you won't run into issues not being able to accept a quest.  If you do accept a quest that is not listed in the guide, write it down because you may need to abandon it in order to keep following the guide if your quest log is full.
This includes the “Tides of Vengeance” campaign missions, which continue the War campaign introduced when the expansion launched. Two new island expeditions called Jorundall and Havenswood were also added. Weekly quests also require less Azerite than they did in the past, Mythic and player-versus-player islands award more Artifact power, and new vendors were made available.
Plus, I am a pet collector, and there are plenty of pets to collect in the new dungeon. Completing the dungeon’s challenge mode grants players a Mini Spider Tank battle pet. Continue playing on a weekly basis to earn currency towards items like the Unopened Gnomeregan Supply Box, Mechanical Cockroach, Schematic: Mechantula, Leper Rat Tail, and Rechargeable Alarm-O-Dog Battery.
The world quests aren’t necessarily bad, but they aren’t good either. I wouldn’t mind killing five of a type of monster or fighting one particular boss a few times, but after seven or eight, it starts to wear pretty thin. But going from levels in the mid-20s can take nearly 30,000 AP, so you’ll need more than world quests if you want to get your heart up in a reasonable time.