This is another one that will most likely be a boon rather than a bane to the player base, though time will tell just how 14years of experience will affect the economy of Classic WoW. There has been no concrete word on just how AddOns will work in Classic, but if the infrastructure of the game works the same as it does in retail, there is a good chance that most of the mods that work in retail will work in Classic. This means that quite a few people will be running around with a whole host of gathering, crafting, auctioning, and gold making mods. Now, those mods did exist back in Vanilla, but not in the same way they do now, and not as many people had them back then as will in Classic. This will drastically affect how effective the auction house will be, and hopefully will affect the economy as a whole in a positive way. Another thing that will most likely see a large increase in popularity is carry runs. These have steadily grown in popularity since Vanilla, and rest assured with the old 40 man raid size that there will be quite a few “Molten Core full carry master loot ON PST for prices GOLD ONLY” being spammed in trade chat. Whether tokens will be available in Classic has yet to be discussed, but if so it will have an enormous impact on the economy of Classic. This, in addition to the differences I will cover in the next section, will have a pretty large impact on the endgame of WoW Classic.

The main topic for Classic at the moment would be whether the game is actually harder or just has more redundant activities you have to do before doing the stuff that's really fun. This is actually a good discussion to have, and not just for WoW, but gaming in general. The main sticking point for now, as most people are on (relatively) low levels is the breaks between killing mobs, especially for mana users. In the beginning it's actually refreshing having to think about what you can and can't pull, not just running into a bunch of mobs and killing them in *insert current optimal time to kill Blizzard determined is the most fun*. The food/drink breaks after a few (or even one) mobs provide time to actually look around the scenery and the mobs you're facing, and while there isn't much strategy involved at these levels, you still at least pretend to plan out how you're going to get to that quest mob without being killed by the 4 random ones surrounding them. Not being able to pull whatever mob you want, and actually having to check what mobs are there when you don't have interrupts yet (casters tend to be a nightmare) is definitely more difficult in a real way than what we have today. As a caster, having to actually think about which spells to use based on mana cost (and perhaps even using lower ranked ones) is definitely more difficult and requires more engagement with your character than we have in modern WoW.
While this might be a change for the better,leveling in Classic will most certainly be different than leveling in Vanilla. In addition to sharding making the beginner zones much more friendly to the hordes and hordes of players storming the gates when Classic comes out, theVanilla leveling process has been studied thoroughly since the game came out 14years ago. Since then, not only have players leveled multiple alts and characters through the beginning zones in Vanilla, but they have done so on a multitude of private servers intended to have the most ‘Blizzlike’ experience. So while leveling a character from 1 to 60 will still be a long, arduous process, it will no longer be marred by mistakes made by players going from zone to zone, continent to continent, searching desperately for a place to level. The zones and routes have been thoroughly mapped out by the Vanilla WoW community at large, and with the internet being much more robust in 2019, that information is just a google search away. Is that a bad thing? I would venture to say that it isn’t, as knowing where to go and what to do doesn’t make it any less challenging and time consuming. It does take away from that exploration aspect,however. You might not have those moments of wandering into Feralas for the first time, or running from Storm wind to Strangle thorn just for the hell of it,or getting lost trying to get to Iron forge from Darnassus on a fresh Night elf.No, those moments, just like many fond memories of Vanilla, are lost in time.
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. 
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.