When hovering over an ability, the tooltip will tell you whether or not that attack is weak or strong against certain pet types. Additionally, you can hover over the opposing team's pets and view their attacks during combat. This will be important since it’s a good idea to pit a pet that's strong against the opponent's pet who's vulnerable to that type.
This spot actually kicks BOOTAY. And I only say that because it's so hidden, unique and quirky that I had to add it to this list, despite it being a method rather than a farm. Generally what you want to do is some sneaky arbitrage. We'll be buying the items Royal olive, Dalapeno Pepper, River onion, and Muskenbutter from the vendor for 2g – and reselling them to the AH for 4g+. This is an awesome way to take advantage of players laziness and the demanding reagent requirements for some of the higher end recipes. By selling from the vendor to AH, you can make easy gold – in fact I suspect most cooks do not know these reagents can be purchased from NPC's.
If you can Solo an instance, you have two options. The first is to take the place apart yourself and sell all the drops on the Auction House. For level 80 characters, Scarlet Monastery, Uldaman, and other mid-level instances are easily soloable, and are a very popular source of cloth and marketable blue and green items. If you're reasonably well-geared, and feeling more adventurous, Scholomance and Stratholme are also soloable, and can be extremely lucrative as a source of auctionable items.
Azeroth paid a terrible price to end the apocalyptic march of the Legion's crusade—but even as the world's wounds are tended, it is the shattered trust between the Alliance and Horde that may prove hardest to mend. As this age-old conflict reignites, join your allies and champion your faction's cause—Azeroth's future will be forged in the fires of war.
Stormheim is the zone you want to start it. For some reason Legion treasures are not worth any experience like they are in WoD...except in Stormheim. I haven't been able to find out any reason for this, and it's possible it may get fixed/nerfed at a later date. But for the time being you REALLY want to jump from treasure to treasure to augment your quest experience.
Some people have made arguments that quest blues can sometimes be more powerful than heirlooms, especially with sockets. I'm not convinced. The simple fact that you never have to even look at quest rewards will save a non-insignificant amount of time over the course of leveling. Also of consideration is the value of enchanted gear never having to be re-enchanted.
Void elf - "Many have sought to harness the corruptive magic of the Void. Most who tried have fallen into madness. Determined to use this power for the good of Azeroth, Alleria Windrunner is the first mortal to succeed at defying the shadow's whispers. Coming to the aid of a group of her kin who nearly gave in to the darkness, Alleria has vowed to train these Void Elves to control the shadows within them and pledge their newfound powers to the Alliance."
Enchants. I honestly wasn't 100% certain which enchants were best, since scaling has screwed up a lot of things. IMO, just pick the enchant for each armor slot that has the highest bonus without level restrictions. The exception is that you'll definitely want Mark of the Hidden Satyr for your neck piece, and probably Elemental Force for your weapon. Both of these proc consistently and strongly across all levels.
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.