Most of the time you spend leveling will involve questing and slaying monsters, but there’s also a lot of travel. Travel earns you little experience (you do gain a bit for discovering new areas), so it’s wise to keep travel to a minimum. The new level scaling system, which scales zones to your level within a preset range, helps with that. You can choose what zones you want to experience and stick with them until you finish their quests.
I've found the best way to level alts is Pet Battling over by Halfhill in Pandaria. My Nightborne Priest I got to 90 that way (the rest was WoD Treasures, then regular leveling post 100), my Mag'har Shaman I'm at 61 with 16 hours or so played. Having a second monitor to zone out and watch Netflix or whatever helps. I think it's the fastest way to get to 90 personally. I really dislike the leveling changes so I just Pet Battle now.
Usually it's best to avoid a lot of instance runs. It is too difficult to account for bad groups, and some instances are too far away with too few quests. Since the experience is very good, it's a good idea to clear nearby instances which have a lot of quests once (Gnomeregan, Deadmines for Alliance). Distant instances with few quests should be avoided (Deadmines for Horde). Low level instances can be cleared by paying or befriending a single high level character. However, since patch 3.3 a new Dungeon group finding system has been implemented, as well as a direct port to dungeons (when entering the group you get ported to the dungeon and back to the same location if you leave it) and thus the travel time to dungeons has been greatly reduced. This makes it a good idea to complete quests or grind while you wait for a group to become available.
I used to use his profession guides they really did help in the pre cata days (before WoW professions site was around) It's really up to you he does keeps his guides up to date and he does he homework (I still get emails) Their are some free leveling power leveling add ons to help you level much like the paid guides. Keep im mind I think he moved to a sub based plan and not a one time payment
Also Alliance currently has a 30% XP buff in War Mode (Horde has 10%) that will last the reset since that bonus changes reset by reset depending on faction participation in War Mode (so next week might be lower, or stay the same, 30% is the cap limit, it will change from 10% to 30% week by week for both factions depending on representation). It works from 20 onwards, it gives you extra abilities you can earn via leveling to use in PvP.
Vol’Dun is the hardest and most tedious of the Horde Zones in Battle for Azeroth. It’s also probably the one that makes the most sense. Each sections of quests leads directly to the one you should do next. For all of these reasons it’s going to be best to get this one done early. Thanks to any legendary items you might have collected in Legion, you’ll be strongest in the leveling process before 115 and weaker after — because that’s when the legendary effects stop working.