Try to gather up all quests for a dungeon before trying to queue up for it. Preferably pick up dungeon quests as soon as they are available to avoid getting them when you are over leveled. Dungeons themselves reward a good amount of experience due to the grouping of mobs, but the quests on top of that reward great experience and decent questing gear.
Again it breaks down to personal preference. I didn’t have an issue doing them at 120 on the toons I did them on. I felt like they took you out of the way when I just wanted to finish the zones. Too each his own. I liked it because I would finish the quest then be right there at the hubs for the quest on the new continent after I’ve finished all the quest on the first continent.
Fourth, beginning in Mists of Pandaria with the Halfhill farm, and continuing in Warlords of Draenor with various garrison buildings that produced resources, Blizzard has been making trade goods more plentiful and easier to obtain. In Legion, herbs, fish and enchanting materials were so abundant that a very small population of gatherers could supply more raw materials than the economy could consume.
He then added, "There is another issue tangentially related to this discussion that I also would like to address: Many feel that it takes too long to level in the 60-80 range in particular, and that the combat pacing issues discussed here are just a piece of that larger problem. We agree – currently players are taking about 15% longer per level, on average, in that range as compared to before 60 or after 80. We’re in the process of assembling a set of changes that will smooth out the experience curve at level 60 and beyond, reducing the experience requirements for those levels."
War Mode, enabled and disabled in Stormwind, gives 15% bonus experience for quests and kills in any zone. whether you're a fan of pvp or not, this might be smart to turn on as Alliance starts on Kul'Tiras and the Horde are on Zandalar. Most horde are going to only be on our island for max level world quests. If you dont like PvP, my advice would be to turn Warmode on for the first few levels, then disable it around 112.