But every new character made that wants to craft old expansion stuff will have to level using expansion specific materials. Stocking up on profession materials that are already high in demand can be a great idea. This will primarily be materials used to craft the various mounts. Ghost Iron, Trillium, Living Steel, Pyrium etc. are all great candidates to stock up on.
Use enchanting to craft tomes of illusions. Every expansion has its own mats, and they're all the easiest thing in the world to farm. You run a dungeon with an enchantor, disenchant everything, gather some elementals or gems for pandaria, and craft a tome which can sell for a good amount if you babysit it well. Sold a draenor one for 22k the other day, and Pandaria ones for 7k and 9k. >THIS IS AN EXAMPLE. If the prices aren't interesting on your server, find something else. It's that simple.<
So much new stuff. The war questline expands. Island expeditions get a couple of new locations to explore. Azerite armor gets tweaked so it’s slightly less stupid than it already is. While we wait for the servers to go back up, Blizzard’s prepared a handy survival guide for Tides of Vengeance. I suggest looking it over, or else risk not surviving at all.