If you bought Legion and have no desire to go through old content, good news! The new expansion comes with a free boost to level 100 for one character. You can buy these boosts from the in-game store whenever you want, but they normally cost $60, so savor this free one. Use it for a class that you are confident you will enjoy. As a fresh level 100 character, you will be able to immediately begin the quest that takes you the Broken Isles, the new region where Legion takes place.
Some players even turn this into their profession by systematically "plundering" vendors in the game world and then selling the items on the auction house at a significant markup. The reason why this works (even for items which are on unlimited supply at vendors) is, that many players don't want to spend time traveling to specific vendors to get hold of a recipe or skill book. They would rather pay a slightly higher price at their local auction house. In some sense, they use the auction house as a "super market" or "convenience store". So it is completely reasonable and legitimate to be the supplier for this convenience store and make money out of it.
Shadowfang is the twink dungeon. You can get a bunch of different valuable twink items here. When soloing at a high level though all items will be level 60, except for in chests. The items in the chests will be around level 20 and those are the ones with the most value. A level 20 Shadowfang will be worth several times what a level 60 one is worth. Bringing a Rogue or someone who can open locked chests is therefor advised.
Okay, speaking of pet farms this one is a really unique farm. What we're looking for is the carrier cage : black tabby. This is a very sought after pet for both horde and alliance – which is why its price competitively at 55,000g. The farm takes place in Hillsbrad Foothills on a peninsula like piece of land just northwest of the yeti caves. There will be dozens of stormpike engineers surrounding ballistas that only horde characters can kill. However, that doesn't mean alliance polayers can't do this farm (im alliance myself). All you need to do is to create a class trial (monk is the best) and send him over to the grinding spot. Use the black ox statue to attract the mobs, and easily maul them down group by group. If luck is on your side, you can make out with an awesome black tabby carrier.
Nearly all quests offer cash or items as a reward, and often both. While completing quests shouldn't be your main form of wealth generation, it is something you are going to do anyway. The key to making the most of quests is picking your reward items wisely. Don't always pick the item that most fits your class - if it isn't demonstrably better than your current item, instead go for whatever reward sells for the greatest amount to the vendor. You can select the in-game interface option to display it in the tooltip. In general, if you can't use a quest reward for your character, pick either a plate-armor or melee weapon as your reward--these tend to sell to vendors for more than other items.
I dont know if this exist already, if it does I couldnt find one, but it would be nice to have a guide with the location of all daily quest broken down by Alliance, Horde, Faction, Neutral, etc. I know there can be variable quest for things like Fishing and Cooking but just having the location for those quest givers would be great. If it were a stand alone addon that would be even better!