Questing and how to turn it into a goldmine.
As many of you already know, at level 70 you get Gold instead of experience for quest payouts.
This is one of the fastest, easiest and most reliable ways to make gold. Some players even choose to level mostly of grind experience and instance runs to save all the quests to make a fortune at level 70.
From my experience, grinding the mobs you need for endgame reputations, as you level from 60 to 70 is a highly efficient way to save the quests and get all your reputation rewards way early.
For example, the Orcs in Hellfire Peninsula all give honor hold or thrallmar reputation. This is a good and easy way to level on until you reach level 63.
The Boglords and Hydras drop unidentified plant parts for Cenarion expedition reputation and are also a very good grinding spot. Not to mention, the bog lords drop motes of life. These can be turned into Primal life and sell for quite a bit of gold.
Following that principle, you can save a lot of quests to do at 70 and cash in.
Then at level 70, with some decent gear and a regular flying mount you can breeze trough most quests and can even do most of the 2 – 3 man ones of the lower 60s by yourself. This allows for big rewards and gold payouts.
Finally, if you don’t want to save the quests as you are leveling, you can try to save the 2 big gold spots: Netherstorm and Shadowmoon valley are the 2 biggest such spots.