Also note that power leveling is sometimes used to refer to paying someone else to level your character to cap as fast as possible (i.e. they power level for you); a distinction used by Blizzard is to refer to the paid leveling as "power leveling service." This behavior is against Blizzard's Terms of Service. Power leveling yourself, which this article covers, is perfectly acceptable.
- The auto trash sell feature is also incredible, but I always had issues with it selling gear efficiently. Often I have to open my bags 2-3 times if I have a lot of trash, because it can't clear it all in one go. There's also a very noticeable delay with this feature when opening the bags, almost like the bag UI is freezing for a few seconds, then it clears. I've started using a different add on for auto selling trash and it does it all instant, no hiccups, no nothing. Just one swift move.
I've used WoW-Pro for years and in WoD, Legion and now BfA it's been awesome for just going on auto-pilot and working your way through a zone. It has 3 levels of depth you can set, so you can set it to just do 1) the main story, main points of interest and rare mobs and treasure that aren't far off the beaten path; 2) every quest with a more thorough dive into the side stuff; 3) absolutely everything.