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.
As late as possible. Early on, you’ll want to follow the missions in Battle for Azeroth right up until you get the option to send a follower on a two-hour long quest. As soon as you get there, stop doing the War Campaign missions. You can come back to them once you have reached something like 119 and a half and finish leveling with those if you want. If you don’t use these missions to cap off your leveling journey, then they’re the first thing you’ll want to do once you reach max level.
It surprises me how this farm was not made public until Legion. It literally slipped through our sights all throughout WOD, where admittedly it would of been a GREAT replacement for the infinite embersilk spot that was quickly nerfed. Anyway, this volatile fire spot takes place in twilight highlands in the humboldt conflagration area – which is a small fire bed with about 20-30 elementals roaming around. Each time you kill you have a chance to recieve volatile fire which is worth 50 – 100g per drop. However, according to my test, the volatile fire has a higher drop chance than the volatile water. I believe this has to do with the popularity of the volatile water farm in WOD, it's popularity may have of gotten it stealth nerfed. Sad to say, but this spot is slightly better in my opinion. REMEMBER to use a potion of treasure finding.
The most simple thing is TradeSkillMaster. This AddOn shows you quite an amount of information in the items tooltip. In my opinion, DBRegionMarketAvg the best source. It tells me the price, an item was posted on all EU realms in the last 14 days. Why not DBMarket? DBMarket only shows you the items value from your server in the last 14 days. This value often gets manipulated. Some people start to post an item with a 500g value for 500.000 Gold on the auction house for several weaks. As a consequence, DBMarket is rising towards 500.000 Gold. If you use DBMarket with 100% and post your item for 500.000 Gold, nobody will buy it.