Blacksmithing is a crafting profession that uses bars obtained from melting ore to craft plate armor and weapons, as well as some assorted cosmetic items. In Legion you craft ilvl 850 gear (demonsteel), a mount and a legendary. These are the main gold making opportunities with blacksmithing. Blacksmithing can also create a lot of transmog gear from old expansion. Some rare recipes have looks that are very sought after primarily for weapons.
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.
Mag'har orc - "For untold generations, the orc clans of Draenor battled one another in endless war. But when Gul'dan offered them the blood of his demonic masters, the disparate tribes of Mag'har—the orcish word for "uncorrupted"—refused the dark bargain and banded together to drive out the Burning Legion. United under the leadership of Grommash Hellscream, the Mag'har pledged to one day repay Azeroth's heroes for aiding their cause. As war against the Alliance intensifies, the Horde must call upon the might of the Mag'har to seize victory."
Vigilance Perch is essentially an automatic mount when out of combat. Despite its tooltip, it only allows you to fly in flying zones, so you will not be able to fly in Battle for Azeroth zones. This is a great Legendary to pair up with Sephuz's Secret. Choosing between this and Apex will come down to personal preference and how you prefer to level. When speed-leveling with consumables, you will not get full value out of the mount ability of this Legendary. If you are just leveling normally, try them both out and see what works best for you.
PLUNDER THE ISLANDS OF THE GREAT SEA – Explore Azeroth’s uncharted isles in Island Expeditions. Battle in groups of three as you race against cunning rival intruders (or enemy players) to collect the island’s resources and fuel the war effort. 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.
Keep in mind that these quests are optional, and are not necessary to continue leveling and capturing companions. They are also account-wide, so if you complete the quest chain on one character, you will not be able to complete it again on another. However, any progress that you've made will be saved and you can pick up where you left off in the quest chain on another character. The dailies that you've unlocked will also be accessible by all your toons.
Any item with a grey name is considered vendor trash or poor quality. White items have some use such as tradeskills, spell reagents or reputation raisers, so you may want to check to see if they're worth more than the vendor price. Keep your eyes out for regular quality weapons, as even the worst of these tend to sell for several silver, or several gold at high level. Always check the tooltip for the vendor price before discarding anything. Also, white (or even grey) shoulder armor under level 20 sells regularly on the auction house, mainly because there is nothing better available at that level.
Cooking is a secondary crafting profession, which is available in addition to your two main professions. It takes various food crafting materials such as meats and fish and turn them into consumable food. The consumables give statbuffs and are used by raiders and other players seeking to maximize performance. It is a great money maker and you should have it on your main.
I recommend not counting on transmog sells for your monthly gametime. Its a great market, but also pretty random. You have to have the right items posted at the right moment if a player needs a certain item. If this is not the case, of course you will not sell anything to him. There are people making millions of golds a month with transmog. But they are very professional at it and it really takes a lot of time.