DMF Cards the first ~72 hours of the expansion. Every deck was selling for 500k-750k after 24 hours, so I spent all the time I had and just shuffled bracers info expulsum. Constantly spammed trade that I was buying herbs at just about every price, and just went to town. Once the weekend hit (Friday), I sold my last few decks (made 44 total in those 3 days I think), and listed all my leftover cards on the AH at a decent cut.
Ya know. It's not the best source of gold, but it's all new gold: Run old raids and vendor all of the gear. In about an hour you can do Highmaul on LFR, Normal, Heroic, and Mythic and get about 6000g total. Some of the other raids aren't quite as fast, but generate similar amounts of gold. You can get some fun new (old?) transmog too if you haven't done much of it.
The thing I liked best about the wide shuffle of those days was that it made ALL of my alts feel valuable. I'd get some ore some was sent to the miner to be smelted and then on to the blacksmith for belt buckles. The rest went to the jewelcrafter to prospect. Some of those got cut, the rest got turned into jewelry that was either sold or disenchanted. The enchanter then converted those mats into scrolls. Meanwhile the army of alchemists transmuted that expansion's elemental material (volatiles, sorcerous, etc). It felt like a whole business operation.
-Azerite Gear- This has been the worst experience for many players as it was advertised as offering the player many options for customizing their character but all players do is Google "Icy veins (Spec/Class) azerite ranks" and select the best one. This is expected and really only gives players the illusion of choice as they're always going to pick the best one. This could have been done far better by not offering necessarily just damage increases in traits but offering some of the Legion Legendary item effects in Azerite slots. You know, certain Azerite traits would be better for PvP, some for raiding, some for 5 mans, some for soloing old content, etc. The other problem with Azerite gear is that it's locked based on you grinding an endless amount of Azerite for your neck piece (basically the stuff that increases the level of your neck piece). So when you get an item that should be an upgrade, it really isn't because you don't have all the traits unlocked. This complaint about how horrible this system is could go on forever, but I'll just leave it at that, horrible.
Mythic+ rewards will also go up by 30 item levels; however, during the first week of Season 2, rewards from end-of-run chests will be capped at Mythic 6 quality (item level 385), and the chest you open next week will contain Season 1 rewards if you do a Mythic+ run this week. (So, for example, if you do a Mythic 10 during the final week of Season 1, you’ll get a Season 1 item level 380 piece and 60 Residuum from your first Season 2 chest.)