My toon was a monk, a class that gets extra experience for an hour at a time. I picked at it more than I have in the past, so I benefitted more from the 150 percent "rested" experience bonus. If I wanted to run a dungeon for quests, I fired up a high-level character on a second account and dragged my little toon through them. And having leveled dozens of characters to 100 and 110, I knew every zone and every objective.
A new expansion unlocks exponentially more powerful gear, letting you easily breeze through Warlords of Draenor dungeons and raids. A great gold making strategy is to solo these challenges and amass a large amount of gold that you get to keep instead of splitting with your group. Start with soloing easy dungeons and work your way towards harder dungeons until you are comfortable enough to take on soloing raids. Speed and clearing ability is key – stick to those you can run through without skipping a beat and you will see your gold making per hour go through the roof.
The guide works great (of course expect a) BUT, after reaching 120 there should also be a guide to open and explore the remaining areas. Also, sometimes when multiple objectives are required, the guide forces you to follow in the order the guide prefers and if you don’t the objective is not rewarded. Gotta start catching up on the followers guides also. All in all, the $47 a year in-game guide is well worth it.