Leatherworking has three specializations: Elemental, Tribal and Dragonscale. I’d pick up Tribal one. It allows to craft Devilsaur set items. Hunters, Rogues, Warriors, Feral Druids, even Enhancement Shamans and Retribution Paladins are among your potential clients. On any realm there is Un’Goro Mafia on Horde and Alliance, they control whole Un’Goro Crater zone and farm Devilsaurs 24/7. They are making thousands of gold. With Dragonscale Spec you are able to craft Black Dragon Mail set. Good demand as well among DPS classes Warriors, Hunters, Shamans, Paladins, for those who wants Bis Pre-Raid items fast and easy. 

Gold in World of Warcraft: Classic can be earned with a bit of luck too. By killing and looting mobs you might find some truly rare items. Some of them might be usable by you but others might not. Don’t just sell that piece of rare equipment to the nearest vendor as it can earn you quite a bit in the auction house. Especially if it’s an item for a level 50+ character.
My main plan will be to focus on raw gold in the beginning. Then I will spend my gold on leveling tailoring and enchanting so I can shuffle enchanting materials which is likely to be very profitable. I already have some shuffle ideas, and I will look for more. Then I’ll work on obtaining the rare enchanting and tailoring recipes to craft those for gold. 
And for talent builds. I prefer to make my own talent builds. But I've been playing RPGs since the 8bit days so half the fun is building my own characters up. I already made and bookmarked 1 deep fire mage build, 2 elemental mage builds, and 2 deep frost mage builds. And I might remake them tomorrow if I read up on any good talent choices I left out my 1st 5 times lol. And I have multiple builds for the other classes I play too.
The leveling guides on my site are essentially speed leveling guides.  My leveling guides are the same guides I use myself to speedrun to 60 on new servers to get 60 server first.  I list many occasions where I tell the player to "die on purpose" to go faster.  I tell the player to skip certain quests, because some quests are just not worth the time/XP.  I list tricks and shortcuts to go faster so you can reach level 60 much quicker.  I am still constantly going through them over and over again perfecting the guides to make them faster and easier to follow.  For the most part, the guide can be followed without the need from other player's help, as the whole guide was made from a solo run anyways.  Although I do list quests that can optionally be done if you have a group.

Who is Joana?  Joana, (AKA Mancow, or FuriousPaul) speedran 1-60 vanilla WoW from 2005 - 2007.  I have been server first to level 60 seven times in a row, along with winning Blizzard's "First to level 50" contest they held back in 2006.  I also have the fastest time through original vanilla 1-60 WoW in 4 days 20 hours. I have produced a very useful 1-60 horde speed leveling guide along with a 1-60 speedrun video. 

Note: My goal here was to create a comprehensive list of everything you'd need in order to learn to play any class (from Level 1 to Naxxramas)—meaning I am only including class-specific resources here (so no profession guides, general leveling guides, etc). Teeb's Resource list is much broader in scope, and I highly recommend you take advantage of it (as it contains a plethora of non-class specific resources as well). If you're not aware, Teeb is also responsible for the Race & Class Comparison Tool, Dungeon Tier Sets Gallery, and a huge variety of other insanely useful resources.
An advice for those who are trying to compete monopolizers: you cannot beat them by selling for less if they follow right steps. You should do opposite: sell for more. Because market will come down if the price goes unreasonably high. You can set a bid on item for the price it should cost and buy out price for higher than a monopolizer is selling. So, common buyer may get an item for the right price or monopolizer has to buy the item at his loss.
I recreated my very first character -- a human warrior, because in the last-push alpha test I joined in 2004, there was no Horde -- and logged in. Immediately, I was surprised by how good the graphics actually looked, for being 15 year old textures-on-polygons. Warcraft's bright colors and cartoony aesthetic continue to this day, so all the increased resolution and better-contoured characters in Lordaeron don't really change the game's visual aesthetic. 
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