Professions: This may seem strange for a leveling guide, but the first opportunity you get, pick up both the Mining and Herbalism gathering professions. Not only will this allow you to track many various quest objectives on your map, but you also get a fair amount of experience whenever you gather. I'd put it at around 10% of a quest turn-in per gather. Since most of your wasted time in WoW is travel time, stopping to gather ore or herbs can keep your exp/h rolling as long as you don't go too far out of your way. You should only gather if it's convenient, and on the way to an actual quest objective. Don't make gathering your priority.
Now that you have the addons and the websites needed for success, you are ready to make auction toons. You will want two auction toons, one on the same faction as your main toon and one on the opposite faction. Do not use your main toon to make the auctions that get you gold! This is one of the greatest mistakes you can make because after a while, people will get annoyed with your prices and selling quantities and begin to blacklist you from groups and some will even boycott your products. Do not risk this happening to you, but rather, create an orc for horde and human for alliance and get them outside the nearest auction houses in Orgrimmar and Stormwind respectively. (As a personal preference, I tend to avoid names with bank, mart, or sell in the name because when negotiating outside of the auction house, you seem less personal). All the addons we downloaded should be enabled for these characters as well.

For the purposes of testing this strategy, I started on a new server (High Pop), and the results have been very reasonable after only 3 weeks. I spent 3 hours farming ZF, 3 hours farming RFK, and then 1.5 hours average in WC the following 2 weeks. I currently have about 250 items up for sale, and have made an average of 20k per day over 21 days. Thats 420K gold over 3 weeks, for about 9 hours of work.

A dungeon should take about half an hour to 45 minutes, that is reasonable. What did we do to Maw of Souls because it was by far the fastest dungeon to spam run for AP? Nerfed its yield. Same happened to dungeons. Except instead of nerfing the XP, they adjusted the clear speed to justify the experience a bit more. Is it perfect? Nah, a lot of dungeons aren't even that long with updates. At most a clear takes 5 mins more.
Most of the players make the mistake of only listing 30-50 transmog items on the auction house and then hoping to get half of them sold until the next day. Me and a lot of other gold farmers and transmog sellers do have 3.000-10.000 items on the auction house across various realms. It does not mean you have to do it that way – but if you have 1000 items listed, chances are higher you can sell up to 10 per day. With only 100 items listed, you have to be lucky to sell one. Of course, the sells are not guaranteed if you post more items. But i’m sure you have a lot more fun if you open your mailbox and 10-20 items are sold