First of all, the value of transmog is decided by rarity and how they look. Some items like Minenarbeithut der Tiefen or Pendel der Verdammnis (they can drop in Uldaman) are worth millions of gold. They are worth so much, because they have a really small chance to drop. Other items are bought well because they look good. Best example in this case is the Glorious set, its legplates Glorreichen Beinplatte reach a 100.000 Gold value easily.
Engineering is a crafting profession that primarily revolves around fun recipes. The gold-making potential from engineering is limited in terms of Legion recipes. The Skullblasters can be obliterated for profit. Engineering has a lot of profitable old world recipes, primarily mounts and various unique effect items and toys. This profession is best relegated to an alt unless you love the lore-aspect or have other sentimental reasons to keep it on your main.
I personally wouldn't recommend Bloodmyst Isle. There's a ton of quests but a lot of those quests have absolutely horrible drop rates on their items. A lot of the quest mobs also have very slow and/or spread out spawns so if there's other people there you're gonna be waiting for respawns or spending a lot of time traveling between spawn areas quite a bit. Overall it's just an incredibly slow zone as far as EXP goes.

EXCEPTION: If you are leveling trade skills while advancing, review the materials requirements of every recipe, pattern, plan, or formula that are planning on purchasing from a trainer. For example, some of the shirt patterns for tailors use very few materials and thus yield a more efficient manner of leveling the trade skill. Check profession leveling guides here on the wiki, ask a guild-mate or friend, or check out information on other web sites to help in this area. A little pre-planning and fore-thought can save you huge investment costs in the long run.
For reference, my previous best time abusing Method-0 in 7.3.5 was 32.4 hours(as show in the old thread). A difference of just over 8 hours; which isn't all that bad, all things considered. And I believe I made several errors along the way, which could be cleaned up in future runs. I believe that that gap could be significantly closed by using a monk's bonus, but I hate playing YMMV
Nov 14 Tabard for reputation not working? I'm wearing the "Tabard of the Argent Crusade". It's descriptions says "Equip: All reputation gains while in lv 80 dungeons will be applied to them." Leveling from 81-85 solely from dungeons... while wearing the tabard and doing random queue for pandarian dungeons gave zero reputation. Anyone know why?Jâck7 Nov 14
With a bit of upfront time investment, and luck, you can kickstart your transmog business. What I recommend is to spend 6-8 hours, or however many you can stomach, farming ZF, WC, and RFK over the course of a week. This should net you a few hundred items of value to list on the AH. Over the coming weeks and months, spend at least one hour per week, revisiting one of these dungeons, or branch out into other classic dungeons.

Congratulations on reaching Level 120! There are a myriad of new things to do. The first thing you should do is head to your faction hub ship where you have been doing your mission table quests and footholds to pick up and complete the quests necessary to unlock World Quests. World Quests will provide you an opportunity to grind reputation levels, acquire gear, and gather Azerite. There are tons of new things to do that we will cover in our Level 120 Battle Guide found here: Level 120 Battle Guide.

Buffs. Food/Flasks/Scrolls/Potions/Elixirs are a small, but noticeable, buff to your killing speed and survivability. If you have a max level character that can already supply you with cooking or alchemy, you'll be very well off, because the AH is a cesspool for this. I can't really give you specific foods or potions to look for, since each AH is going to have different supplies. Generally speaking, lower level foods are going to only last 15-20 minutes until you can buy the more powerful versions at 60+. Look for anything that adds versatility or your primary stat, and buy stacks for each level range(1-60/70/80/90/100).
While leveling, try to make use of the new Battle of Azeroth experience gem, Insightful Rubellite, which gives you +5% experience. Equipping one of these requires a socket in your gear, so try to hold on to a piece of Legion gear with a socket or acquire one of the Legion Legendary rings since every class has one. Each of the rings includes a socket. You can acquire one of these rings rather easily by doing World Quests in Legion zones and acquiring 1,000 Wakening Essences that can be used to purchase a legendary ring in the Legion version of Dalaran.
If i start on a new realms, I am farming a lot of transmog from classic and Burning Crusade Dungeons and Raids. In the beginning, i start to post them if they have at least a DBRegionMarketAvg (Average value of an item on all EU realms of the last 14 days) of 500 Gold. All the other items get vendored. The time you hit a stock of 1000 Items, my value treshold raises to around 2.500 Gold. All the items below that value get vendored aswell. Newly farmed items that are above these treshold will be listed. Why? If I start over somewhere, I want to get a certain amount of gold quickly. Cheap items are great for that. Later on, to save time, Quality is better than quantity. As mentioned above, re-posting the items on the auction house takes quite a bit of time. At this point, I can recommend you the TradeSkillMaster AddOn, it makes your auction house work really a hell of a lot easier.