Stop transmogging. Seriously, when I was saving for longboi I stopped transmogging for a few months. It’s worth a lot.
Callings. These things just throw gold at you.
Sell crafting mats. You don’t even have to farm them this expansion for a bit of extra cash. Just all the meat, fish, cloth, everything else that you just passively collect while playing. Slap it up on the AH.
Professions. Always the most reliable. I finally got around to leveling inscription last week. Missives are a very reliable source of income. Nothing life changing. But they sell.
I posted that in a thread last week. There’s a lot of advice from people in there.