Unless low quality items have some known quest use or are coveted by other players, you should try to sell it as soon as possible to create bag space. Always (or almost always, see above exceptions) keep things like cloth, leather, herbs, or large stacks of white/gray items over other loot when you have to decide what to keep when your bags get full. It might be worth your while to invest in larger bags (10-20 slot), especially if you know a tailor.
Now lets get to a "math". You need 10k reputation for a cache. For a daily emissary quest, which gives the rep the fastest way you receive 1.5k reputation. Since the quest needs 4 of the world quests for said faction, lets total them up to 500rep which gives 2k reputation for an emissary cycle. Lets optimistically say that you require 3 minutes to reach a world quest and finish it, totalling at 12minuter per 2k reputation. It would mean that you spend an hour total on a chance to get up to 5k gold. Ofcourse there would be some exceptions to that, such as tortollan quests that need only 3wq, rare quests that give extra rep and more rep in general or for example follower missions for extra rep (but those require resources). But there is also a fact that you might take more than 3 mins to finish a wq which negates that.

Enchanting is a crafting profession that allows you to enchant gear with stat increases. It also allows you to disenchant gear for crafting materials. Enchanting uses crafting materials that can only be obtained from disenchanting gear. This means the only source is either crafting yourself or buying from other players. As the profession mostly revolves around stat increases only the legion recipes are relevant. Enchanting is also a great source of obliterum. The other ways to make gold with the profession is crafting and selling enchants and doing the enchanting shuffle.

Majority of world quests provide pretty bad rewards. Running for a wq that rewards 130 gold is a waste. Resources are not that necessary apart of some rare profit missions or buying the seal for them. Azerite for non-raiders or nonmythics is pretty much useless to farm since every patch will lower their requirement, and aside from few occasions it brings not much of a value. Not to mention that island expeditions are probably easier/faster with rng chance for tmog or pets. So the only main reason to farm them is the reputation. The most important is getting to exalted for recipes but for that there is no cache. The rest is pretty much not needed.

Different qualities aren't limited only to wild pets—many rare World drops and special non-wild companions have had their stats boosted. For example, the world-drop dragon whelps (Azure Whelpling, Crimson Whelpling, Dark Whelpling, and Emerald Whelpling) are of [rare] quality. Check your Pet Journal to see the color-coded rarity of your non-wild pets.
Combat is turn-based and there is no time limit on each round in a PVE Pet Battle. You can take your time to determine which spell to use next. Some pet abilities have multiple round cooldowns, while others can do extra damage if certain conditions are met. Be creative and have fun testing which combination of attacks works best against different wild pets!
Assuming, worst case, procs of 30 monelite ore, in my server they sell for 20g each, so 600g per proc. 5325 divided by 600 is 8.875 missions, rounded up, 9 procced missions in order to make even with pick costs. EVERYTHING after that is pure profit. Its important to remark that the chance is far from 100%, some people say as low as 10% to proc but I didnt find any hard data on this.
Nov 13 What are the differences between versions? I just have a trial at the moment but i'm confused on what each version offers. Normal Sub : $15 a month Battle for Azeroth: $50 (needs subscription) Complete Colelction: $60 As far as i knew if you had a subscription to the game you get all of the content minus the latest expansion. So let me see if this is right. If i were to get the complete collection i would get one month at a $5 discount and the newest expansion OR Just pay $15 For the game and all expansions EXCEPT BFA?Buresh2 Nov 13
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.

If you queue as a healer - take care to always have a stack of water of appropriate level. You can buy it at an innkeeper for next to nothing, but remember that it will become too low-lvl for you very fast, so you need to buy new water every 10-20 levels. Alternatively, you can buy a stack of every tier of water in Stormwind, and just always carry it with you. Another alternative, if you see a mage - always ask him (politely) to create a table for you. Grab 2-3 stacks so you have extra for the next runs.  

The last farm on this list, actually I was surprised this farm eluded me for so long.  Generally speaking gnomergan is a huge confusing instance that takes some getting used to but if your a high value transmog farmer this does not scare you.  You can pull the entire instance and get access to a plethora of high value loot such a recipes, world drops, greens and even engineer supplies.  Overall this farm is shadowed by the Diremaul farm and Zulfarrak farm, but is an equal change of scenery with a wild card if you get the hot shot pilots gloves OR the mechbuilders overalls worth 400,000g and 60,000g respectively.  A pretty cool neat farm that noone really mentioned until now.

XP Potions: The Elixir of Rapid Mind and Elixir of Ancient Knowledge no longer drop. They can be bought on the AH still but are way to expensive for it to be worth it. The Excess Potion of Accelerated learning is available from your garrison quartermaster but only works for level 91 to 99. As of Patch 8.1 you can also buy the 10% XP Potion Draught of Ten Lands.

Island expeditions - Set sail for the previously unmapped isles of Azeroth. Battle in groups of three as you race against cunning rival intruders—or enemy players—to collect the island's resources. Constantly evolving challenges await as you traverse frozen landscapes near Northrend, open the gates of an abandoned Gilnean castle, navigate a war between elementals and more. Can be done either in PvP or PvE against advanced AIs.
Okay, this farm really picked up steam here in late legion.  Generally what we're looking for is volatile air, and other volatiles when combined with the potion of treasure finding.  This farm is as easy as pulling the entire instance all the way to the first boss – and AOE'ing down ebery mob that follows.  In the video you can see me getting volatile airs in stacks of 11 for each pull I make.   Wit the trending price of each volatile being worth at least 100g, I was making 1100g per pull.  It's by far the most effcient volatile spot, but it has hits limits as you can only reset an instance 10 times before you have to wait a while to do it again.  If you only going to be on for an hour or so, this is the spot you want to hit.  It's great, fast, and awards a high liquid value of items.  Awesome Stuff.
These books cost 1.000 Gold each and are sold from your BfA gathering profession trainer. As soon as you re-learned your farming profession, use this book and you will get back all of your lost Battle for Azeroth gathering ranks. Your gathering skill remains reset at 1, but you don’t have to care about that since you have your ranks back – thats literally all that matters.