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.
Still, it’s terrible to see the new expansion fail so spectacularly at iterating on Legion’s success. It’s hard to believe the two expansions came from the same company. Legion made you feel powerful and unique. Battle for Azeroth grinds at you by taking away as much as it gives. Sure, you can have a shiny toy. Sometimes. If you don’t get too carried away.
Warfronts are larger, 20-man instances that take inspiration from the Warcraft strategy games. Players are deployed on the Warfront to collect resources, destroy enemy troops, construct buildings, and eventually launch an assault to take over the enemy base. These battles take 20 to 40 minutes to complete and, unlike Island Expeditions, don’t offer a PvP mode.

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.