Step-by-step class guides are on the way!  The 1-12 Mulgore Guide is the first guide to get all the individual class steps.  At the top of the guide, simply select which class you are playing and the page will dynamically update all the steps in the guide for that class (both text and images).  The rest of the guides will be slowly updated overtime to include all the class steps, but you can see how it's going to work with the 1-12 Mulgore.  I want to thank crazyK and his Placeholderguild for helping me out with the individual class content.  They are allowing me to get the 1-60 Alliance guide done while also getting all the class steps done at the same time, so everything can be ready for Classic launch (hopefully).
First thing you should do is to learn the market for the specific item you would like to monopolize. Let’s say it is Kingsblood. We can see a stack of Kingsblood is selling for 1 gold. There are 10 stacks on Auction House. To control the market, you have to buy out all the lots of Kingsblood, even single ones. Next move is to make auctions of Kingsblood you have bought for the price you want. Be reasonable and make it 2 gold. But all people are still being used to the old price of 1 gold and will not buy your Kingsblood at first. You have to maintain your auctions for 2 gold all the time, no need to put all Kingsblood you have at once, 3-5 lots are enough at the beginning. You can see, other sellers may start create auctions for 2 gold as well. That’s what we need.  But if someone is selling for cheaper price, buy out their Kingsblood immediately. Soon people will start to accept your price of 2 gold as a regular price and will buy your stuff. Now you just to have to sell all Kingsblood you got. Control several markets. It can be anything, even twink blue items or items level 20-30 or 30-40. Same strategy works everywhere. It requires lots of time to track the markets and check auction house. It is not that easy as it may seem, you should spend at least a week of monitoring to be sure about prices, you will fail if you buy out everything at once without research. Soon or later, too many people will decide to sell your item as well. As they could see price change and think it had happened naturally. Market becomes overflooded. It is important to quit before the collapse. This always happens.
They seem to have expected some things, though, see adding pets with aquatic damage (gun and ooze) aswell as a resistant cockroach to stop us from cheesing everything with elementals. Yet, a fact their damage output is low combined with shields not checking for racial damage means this mechanic prevents a lot as you mentioned. The last boss has got an ability to remove basic shields so perhaps that was not in oblivion either… unlike the reactive damage. Also, an ability that forces swap altogether with an ability which prevents from being swapped, including critters? I can't say I like it.
Furthermore, we highly recommend you plan in advance regarding the class that you want to play. In the Classic WoW, there were no class specs. Every talent point spent couldn’t be changed without first resetting all of them and the talent point reset was a costly practice. If you already know what you want to play as in the end game – try to develop your talent tree accordingly. This way you’ll be able to save a lot of gold in advance.
Kaivax, a WoW forum community manager, revealed that WoW Classic's class design, battleground mechanics and stats on existing items will be set to their 1.12 state, despite the game releasing content that expands beyond that. This removes "progressive itemization," so if the stats on a specific piece of equipment was changed during the original updates, that won't take effect in this version.

Blizz stated in a watercooler that they're using the 1.12 database as a starting point. I don't think it's a stretch for people to assume that most game features and mechanics will be in their 1.12 state. The kind of stuff I would expect to see reverted would be numerous AV changes, but I seriously doubt class mechanics are going to be reverted. I'd be surprised if the threat changes that ruin pre-naxx encounters are reverted.

I think that the token is a nice solution for the problem. Back in the days, blizzard tryed to ban gold sellers, but it was a lost cause. Instead, the token seems to have resolved the problem, letting workers that want to raid with consumables and stuffs to have the golds to do it. Personally, I don't find the gold buying really fair, but I understand that for many people is a necessity and I prefer to leave the economy and the farming spots to the player instead to the gold sellers.

The Horde levels 50-60 guide has been rewritten and revamped.  My 1-60 Horde leveling guide is now completely updated for the 1.12 Drums of War patch.  As you can see it is about 15% larger than the 40-50 guide (single largest guide page yet).  There is also a lot of route changes.  I moved the entire Silithus section from level 55 to level 58, which allowed me to include a lot more quests for that zone.  There is also a lot of other improvement to the route, including adding a lot more quests into the guide, mostly from Moonglade, Silithus and Eastern Plaguelands.  This will make the final level 59 grind much shorter.

Where to get materials and reagents you may ask? Buy for cheap off farmers in bulk or track Auction House lots. Get in touch with most big sellers. Communication is important here, send a whisper or write them a letter. It would be good for both of you to establish business relationships. Constant suppliers and buyers is convenient for both parties to save the time and effort.
The quickest way to level up is to travel through the game's zones, completing all the quests you encounter along the way. Completing quests grants you Experience points, which will slowly fill in your experience bar with blue or purple. When the bar fills, you reach the next level. Alternatively, you could choose to run Dungeons or Battlegrounds, which are not covered in this beginner's guide.
Another way to make gold. This option works well at level 60 when you have some good gear already. Obviously, you should have some gold ready to buy reagents. Be ready for expenses up to 225 skill points in any profession: items below that are not worth much. You will get first income after 225 skill points in Leatherworking, Blacksmithing, Alchemy or Tailoring. Unfortunately, Engineering and Enchanting will still require some investments.  The only way to make gold with enchanting is disenchanting skill (we talked about it).