So, what is the fastest way to level in WoW? Well, the short answer is questing. But not all quests are created equally. To know which ones to do, you'll need a leveling guide.
These guides give strict instruction on which quests to do, in which order. But not all guides are created equally, either.
So the question "What is the fastest way to level in WoW?" becomes "Which WoW leveling guide is the fastest?"
The popular contenders are Joana's Horde Leveling Guide for Horde players, its very similar counterpart Brian Kopp's Alliance Leveling Guide for Alliance players, and Team iDemise's Alliance and Horde Leveling Guides for either side.
There are other guides out there, but these are the ones I've used that are contenders for the title of "Fastest Way to Level in WoW"/"Fastest WoW Leveling Guide".
Now, I could go into a bunch of the pros and cons of all these guides here, but I won't since I already did that elsewhere.
Instead I'll just say it: Team iDemise is fastest. Assuming ideal conditions, any of these three guides will get you to 80 in very similar times. But the iDemise guide is the only one that actually CREATES the ideal situation. It eliminates the need to go back and forth checking the guide by putting everything in-game with a mod, and it helps make sure you are using the ideal talent build for quick leveling, a factor many don't take into account.
So there you have it. The anwer to the question "What is the fastest way to level in WoW?" is answered with the question "Which WoW leveling guide is the fastest?" which is finally, in turn, answered with Team iDemise's guide. I hope this article has helped you accelerate your leveling some!