Since you’ll already have to complete quite a few World Quests to reach the required reputation levels for the previous achievement, this one should come naturally. It’s worth noting that this achievement specifically requires 100 different World Quests, so if a World Quest pops up that you don’t recall having done before, it’s best to head out and knock it off. Completing "Beachhead" 100 times just won’t cut it, but Scrollsage Nola certainly appreciates your efforts.
Once you get to about 200g, the theoretical limit of your profit virtually disappears. You now have enough money to start mass buying and reselling those players' goods who undercut everything by an extreme amount. Enchant mats are still a very good focus during this period, especially essences and crystals. You can now afford to buy several maelstrom and abyss crystals and wait until prices fluctuate to resell for a profit. A major strategy you can begin to employ is the multi-character trading and auctioning. If you come across 5 abyss crystals, get onto one character during peak hours and advertise a price 25-50% higher than average. When no one responds to this, quickly switch to another toon and offer the same 5 crystals for 10% lower than before. This will help to raise the median price because other sellers see what they may be able to get for their good. While they are cancelling and reposting, take this time to undercut their new prices, which is now more than you ever could have gotten before when prices were low. If you master this with BoE epics or more rare items, then you can make differences of thousands of gold.
This leaves players chasing an endless loop of trying to get higher level Azerite gear — which can only reliably be gained through raids and isn’t available in Mythic+ — but only the pieces with exactly the right traits will actually be an upgrade. It’s even possible that some items that should be huge upgrades are nullified by the loss of a specific trait that makes one ability do more damage than the others.
Once you reach 575 you can purchase vendor recipes for the last 25 points. The Blacksmithing recipes are on a vendor in Vale of Eternal Blossoms. You can enter Vale of Eternal Blossoms after completing the questA Celestial Experience (requires level 87). After you completed the quest, you can find Jorunga Stonehoof (Horde) in Shrine of Two Moons and Cullen Hammerbrow (Alliance) in Shrine of Seven Stars.
From “The Burning Crusade” expansion, weapons like Klinge der Zauberei, Die Nachtklinge and recipes for different weapons are really valuable. The best example is Pläne: Teufelsstahlangschwert, worth 500.000+ Gold. These items are World Drops, you can find them in all raids and dungeons. I don’t know any Open World Drops, but that does not mean there are none. Another great transmog source are world bosses and rare spawns on Outland.