This farm very much resembles the Dire Maul farm in that it allows you to hit multiple markets without having to do too much.  You can mageweave, runecloth, greens, world drops, and herbs all from this one single spot with the addition of countless transmog items.  I personally love this spot – however I feel I stumbled upon it a little to late.  The benefits is that this is the LARGEST instance in the entire game – literally.  You can spend up to 15 minutes pulling the entire instance.  You are rewarded however with an abundance of drops of all kinds. You can quickly fill up your inventory here.  If you need greens form the 47-51 area, this is your spot.  As mentioned, you will also get soo many trade goods that it's hard not to fill even the biggest of bags.
Elemental items (Primals, Eternals, etc.) can be a good source of money, because they are always in demand on the AH. See which mobs you will most benefit from farming, then set out for a few hours. In the process you will also most likely collect significant vendor trash, and may get other profitable item drops as well. Note, however, that older elemental drops usually lose profitability compared to newer ones, i.e. Primal Water sold well to level 70 players in BC, but sells far less well to level 80 players in WotLK, because level 80 gear requires Eternal this'n'that.
Mining is one of the three gathering professions in the game. You mine from ore deposits for all the various ores in the game. Your customers will be blacksmiths, engineers and jewelcrafters. You can make good gold per hour from tons of different routes both farming for legion ores and farming old world ores. I personally don’t farm, so I can’t tell you the best routes, but check out Oldbess guide on mining for some great spots.
If i start on a new realms, I am farming a lot of transmog from classic and Burning Crusade Dungeons and Raids. In the beginning, i start to post them if they have at least a DBRegionMarketAvg (Average value of an item on all EU realms of the last 14 days) of 500 Gold. All the other items get vendored. The time you hit a stock of 1000 Items, my value treshold raises to around 2.500 Gold. All the items below that value get vendored aswell. Newly farmed items that are above these treshold will be listed. Why? If I start over somewhere, I want to get a certain amount of gold quickly. Cheap items are great for that. Later on, to save time, Quality is better than quantity. As mentioned above, re-posting the items on the auction house takes quite a bit of time. At this point, I can recommend you the TradeSkillMaster AddOn, it makes your auction house work really a hell of a lot easier.