As you level, you will buy new ranks of spells. If you splurge out on an item upgrade, you will not have enough gold readily available to upgrade to the latest ranks of spells: placing you behind. Moreover, you can buy gear upgrades from the Auction House (AH) or vendors. Furthermore, you may have large investments that need to be paid for professors. You will need to purchase reagents and items such as leather, bolts of cloth, alchemy supplies – unless you have a charitable friend or another high-level alt.

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.

Druid is one of the most versatile classes across all of World of Warcraft Classic. By picking Druid you will have plenty of options to choose from while leveling. However, in the end-game, most groups will expect you to heal, though, Feral and Balance druids are also very desirable for their Innervate and Rebirth abilities. Additionally, various animal forms will make traversing the world into quite an uncomplicated task.
It is also worth noting that World of Warcraft Classic isn't exactly an archive from 2006. It has been rebuilt from patch 1.12, using modern data architecture and reaps the benefits of the modern engine. This means a lot of non-controversial quality-of-life features will still be present and it is possible to run WoW Classic servers on modern server architecture. As you can imagine, much has changed in the last 13 years in the tech space. That's before smartphones were even a thing. The modern engine no longer allows certain behaviours that could be used to get out of bounds, also adds widescreen monitor support and accessibility options! However, it does have the disadvantage of not being able to run on 32-bit systems which isn't that kind to older systems considering the game is from 2006.
Our initial runs exposed a few (expected) issues: the game sometimes crashed, didn’t recognize our modern video cards, and was incompatible with our current login system. That first pass also couldn’t support any of our modern security and anti-cheating capabilities. Clearly we had a lot of work to do to make WoW Classic live up to the Blizzard standard of quality, and deliver the experience players want.
I made some route changes to the Horde levels 43-44 sections.  I have swapped 44 Dustwallow Marsh with 44 Desolace (the entire sections). This allowed me to do Deadmire (at lvl 43 instead of 38) and then go stop at TB to turn in Deadmire + The Black Shield at the same time, then fly quickly to do the Desolace stuff.  Doing 44 Desolace is now mandatory because I think its faster with the new routes. This will also make the level 53 grind much shorter.  I think these were great changes.

Wait, /sit to trigger crits is p-server thing? I distinctly remember people saying that if you sit, you will be crit when I played 1.12 Vanilla. On top of that - there’s that pally that one shot Kazzak in early Vanilla because he stacked a shitload of reckoning when it didn’t have a limit - it’s not inconceivable that he did it without /sit to trigger crits, but it would take him so, SO long to do that without /sit.
You will need initial funds to start this way. Buy for cheap and sell for actual price or higher – that sounds pretty easy. But you should have basic knowledge of prices and always track the market. People use to sell for cheap when they need fast gold or don’t know real value of the item. So, it’s your chance to act. If you see anyone selling an item for low price in trade channel, contact them immediately. You should use all of your trade skills to negotiate about the price to make it as low as possible. It’s important ability to communicate. Besides, it’s good to get addons to trade effectively on Auction House: Aux or Auctioneer. They allow you to scan auction, compare prices, find cheapest options, post items quickly, and many other useful tools. It is possible to make your first thousand out of ten gold you have in a pocket.

In the past, if someone accidentally looted something they didn’t mean to in a group, players would have to contact customer support to trade it. In the modern system, players are given a period of time in which they can still exchange loot with others. This is a convenience we felt was worth retaining for Classic rather than making people go through customer support. (Sorry ninja looters!)

Nov 15 You Absolutely Cannot Have Sharding This will not work well with a classic experience. Myself and the vast majority of my friends plan on coming back for classic. None of them want sharding. I know I don't speak for everyone but this mechanic will completely ruin the experience. Just voicing my opinion as I am incredibly excited about this project.Wurmknight82 Nov 15
Beginning May 15, select WoW players will be invited to participate in a small-scale, focused closed beta test. Players will also get a chance to help put our servers and technology through their paces in a series of stress tests running from May through July—you can opt in now through Account Management and select the WoW Classic beta. Subsequent stress tests will extend the opportunity to even more players. Level caps will also be in place to ensure we’re emphasizing the “stress” in “stress test”
Expected More That WoW Classic Will Resurrect That Hardcore Breed Of MMO That So Many Players Originally Fell In Love With. In World Of Warcraft Classic, It's Built Using Patch 1.12, Titled Drums Of War, Released On August 22, 2006, Equipment And Abilities Will Remain Stable In Order To Reflect The Minor Adjustment That Blizzard Made With Each Path While Dungeons, Raids, And PVP Features Will Constantly Change.
Some class systems from the original game simply don’t have a modern equivalent. The class probably most affected by this is the hunter. The pet happiness and loyalty systems were removed a long time ago, as well as pet training and the ability to use both a ranged weapon and a melee weapon. In these cases, converting the old data to the new system wouldn’t work, simply because there is no new system to match. In this instance, we had to bring back the old code—and we did. Fortunately, the restoration went smoothly, though the reality of having to buy arrows or feed their pets again took a few people in our internal tests by surprise. 

Once we had our starting point, we began taking stock of what we had in the source code and what we could make available, which included restoring the original development database from archival backups. After stitching various key pieces together, we had a locally rebuilt version of Patch 1.12 running internally. The team could create characters and do basic questing and leveling—and dying, which we did many times. For testing purposes. Obviously.

Nov 15 Classic Box Cost Disappointed in the decision to bundle the subs and (at least for now) not have a separate Classic sub option. That said, can we at least get a separate box cost for access to classic? It would: - help alleviate temporary bloat and subsequent dead realms - servers would be more stable population-wise over time - remove the bulk of the need for sharding - give a solid idea of how many servers will be needed - allow blizzard to set up a separate classic forum for those with a monetary commitment - with a separate forum group, feedback would be limited to those with a vested interest The subs would still be bundled, but there would be a box cost, akin to what one would have to pay for BFA access. A very good to-the-point post from later on in this thread:... Another good post about how the current setup would necessitate sharding:... A decent (albeit short-term) alternative:...Brokenwind314 Nov 15
Nov 15 Loot sharing. Fools How stupid is the community about loot sharing? You know there is master loot right? Stop being dumb guys like holy crap. You also know that if you're the guy setting up a group or joining a group you have a option not to run or you can pick player's of different armor types... If you're a cloth wearer you just don't run or set up a group with other cloth wearers. Like this is something so simple and the community can't graps anything. I feel bad for blizzard sometimes with having to deal with brain power of this community. The community: "Oh, I didn't think about that. Derp, I'm an idiot."Plewtoe23 Nov 15
As of right now, there is no official exact release date, aside from confirmation of summer 2019. It is expected to hit the internet roughly mid-July, or possibly in August. Something as highly anticipated as WoW Classic could launch with weeks of notice and still break records. As of April 21st 2019, World of Warcraft Classic has entered internal employee alpha testing.
Nov 15 The most hardcore thing you can do. In vanilla? I have a few things that could be it. Playing on a perma death PvP server and kill kel'thuzad. Without dying even once. Being able to kill a mage/rogue/warlock/pally in all BiS gear Soloing a high end dungeon boss like rivendare or dark master gandling. Leveling to 60 with no gear or weapons or pet of any kind. That is by far the most hardcore, life threatening thing you can do in vanilla wowHavell7 Nov 15
Most profitable professions are considered to be Herbalism and Enchanting in pair. You can have Enchanting only for Disenchanting skill, it will bring decent gold. Consider the fact of disenchanting all soulbound armor, not just selling them to a vendor, but I do not recommend to disenchant any kind of weapons, it is more profitable to sell it to a merchant if it is a soulbound item, or sell it on auction house if it is BoE (bind on equip).
While our initial effort helped us determine the experience we wanted to provide, this second prototype really defined how we’d get there. Starting from a modern architecture—with all its security and stability changes—means the team’s efforts can be focused on pursuing an authentic classic experience. Any differences in behavior between our development builds and the patch 1.12 reference can be systematically cataloged and corrected, while still operating from a foundation that’s stable and secure.
Nov 15 To all of you who keep talking $$$ Please do explain why a company should waste money to appease you ? I commonly see things like "zomg blikky made 12 bazillion dollars last financial year" "haii why so cheap daddy blizz, please release 500 low pop servers on release , so you can spend the next year wasting money and resources " Grow up. Thanks.Azerothian30	Nov 15 

Even though the guide was developed with a hunter, the guide can be followed by any class.  Except you have to do your class's quests which aren't a whole lot.  I do have full intention to make my guide friendly with all classes in the future by listing all of their steps as well.  There will be a toggle that allows you to show which class's steps you want to see in the guide.  But this is coming later.
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. 
HOWEVER, I did find out that there was an exploit to get around it (one of those rare exploits where you would WANT a bit of lag). Basically if you spammed “X” to sit/stand/sit/stand, then if a mob hit you while you were sitting and right as you were standing up, then it would register as a crit, but on the server side you would be standing, thus allowing the ability to proc.
The priest was considered the best overall healer in vanilla WoW. Priests had the biggest selection of healing and defensive spells which could be used in various different situations. Due to this fact, Priests had an easy time finding groups and guilds. If you’ll embark on leveling priest, expect some random whispers from other players inviting you to join their group as a healer. Shadow Priests were also considered as one of the best duelists in the game boasting with serious damage and healing.
Earning gold in World of Warcraft: Classic is all about optimizing your spendings. Back in the day, your character’s skills were acquired from a trainer, using money. Don’t just buy everything he or she offers! Read the skill descriptions and be mindful about them. Quite a few characters can live through the levelling process without learning some of their utility or damage spells. These won’t go anywhere and you’ll be able to learn them later on.
There is an Action Bar at bottom of the User interface. Each class starts with some skills. Every few levels, you will unlock new skills specific to your character class, these can be learned from your Class trainer. You will be introduced to one of these NPCs during one of the first few quests you complete in your starting zone, but they can also be found in many towns and each of your Faction's cities.