Sky Golem factory; Use all your spare alts to craft those. Level their Pandaria engineering to 75 by farming ghost iron ore (mostly) and start doing their daily CD's. It's super easy to find informations on how to do it quickly, look it up. 4-5 alts = 4-5 golems a month = a million gold a month if golems go for 200k+ like on my server (250k on mine)
Despite all of these problems and this laundry list of glaring systematic issues, the crowning achievement of Battle for Azeroth’s endgame is that it still remains enjoyable all due to those two pillars of raiding and dungeons. That won’t last forever. As the expansion goes on, and the grind necessary to progress becomes even more demanding and the time spent in content that simply isn’t fun increases, it will be harder and harder for raiding and Mythic+ to carry the expansion along. 

Don't get me wrong, I'm not turning my nose at people who struggle to do well (I'm not exactly a mastermind myself), but the legion expansion has made people lazy in terms of finding their jackpot system. We need to get used to gold making going from the "all for all" system to the current "all for one" system and the first step is understanding that the WoW economy is never decidedly made good or bad as if it somehow exists along the same lines as class design and gameplay mechanics.
This gold making advice is applicable to most players, except if you are an enchanter, in which case there is a very strong case to turn them into dust and essence for your profession needs. As an advanced tip, you can explore the use of mobile apps that let you post on the auction house at the right time because the price of greens tends to fluctuate rapidly, and could mean a large loss of potential gold income.

All of my gold came from everyone buying stuff at a really marked up price for instance BS 2h mace if it proced epic i was making at least 125k per one and i was making batchs of 10 to 15 it was like 25k for blue and 125k+ for epics at the time. And i was buying the ore for like 16g to 40g a pop so huge profit. Im still trying to figure out what im gunna do now to rebuild it will be a slow process now.