So you are coming back to WoW after taking an expac (or two) off, or you are a new player. Maybe you just never bothered with making and maintaining a gold reserve. Let me highlight a few things you can do to quickly get some coin in your pockets.
Take two gathering professions. You can drop one, once you figure out what you want to use your second profession spot on. This will give you mats to use on your professions and sell on the Auction house. My advice will be to sell off all your mats. Even if they have a “catch up” mechanic for Warlords, there were be plenty of people making stuff or leveling up the “old fashoned way”.
Go to the Timeless Isle and loot all the easy chests you can find. Need help? Check out this nifty guide. Don’t worry about fighting mobs, unless you want to hone your new class skills. You won’t need the gear*, so open all you can and vendor it. Easy money.
Run old dungeons/raids for mats, drops and pets!
Do a couple dailies. Especially the easy ones. You will need some quick gold for repair bills and flight paths. You could do worse. The Dalaran fishing dailies are still easy to do and you can get some valuable items in the fishing cache you get from completing them.
Get bigger bags. It’s a good chance your newly boosted toon will not have a set of 20-22 slot bags. Once you get some gold going, you can purchase the mats off the AH and have someone craft them for you. Or you can go grind out the embersilk or frostweave. Unless you have a mount with a vendor, the more you can carry, the more you can sell!
*Unless you want to upgrade your “boosted” gear. If you go that route, don’t open the Timeless gear until you have a burden to use on it.