Mythic+ has some similarity to raiding, but it’s designed for just five players, instead of the 10-to-30 that can make up a raid. This mode tasks players with clearing the game’s dungeons, but with specific changes that make them harder, scaling up until it’s impossible for groups to finish. Players receive a keystone in their inventory that assigns them their dungeon, one of the game’s 10, and gives the dungeon a level. This determines how difficult enemies are and what effects might make them harder. If the group completes the keystone in time, they get a new, higher-level stone; if they, don’t they get a lower-level stone.
Once again, as soon as you hit 70 - I recommend to go and learn faster flying. This speeds up your questing A LOT, and is worth the time and gold. It will cost 4500 if you go to the capitol, or 5000 if you prefer Shattrath/Dalaran, because you will not have reputation with them at that point. This price will sadly be above what a totally new character can afford, if you don't have any Main. But you should go and buy flying as soon as you have enough money.
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.
EXPLORE TWO FABLED KINGDOMS – As a champion of the Horde, travel to Zandalar to persuade the trolls to lend their naval might to the war effort. As a defender of the Alliance, sail to the seafaring kingdom of Kul Tiras, home of Jaina Proudmoore, and rally its inhabitants to fight for your cause. Once you’ve successfully recruited one of these proud kingdoms to your faction, infiltrate the enemy’s newly claimed territory.
If you want to spend as little time on your alt as possible - just do Legion Invasions. You can use sites like (https://wow.gameinfo.io/invasions) to track when the next invasion will be. Log in, fly to the closest world quest, and once there - right-click on the quest's name in your quest log and "Find Group". Sign up for some group, or if there's none - just start your own immediately, and people will come to you. It is 10 times faster to do invasion quests in a group. Once that particular quest is complete - leave the group, and fly to the next one, where you should find another group. Don't expect the group from one world quest to follow you to the next. Then you simply log out until next invasion. You can do 1-2 invasions a day, and each invasion will give you about a level or 1.5 of experience, if you have full heirloom gear. Each invasion will take about 20 minutes.
That lack of storytelling agency may soon change with Patch 8.1, Tides of Vengeance, which is coming to Battle for Azeroth soon. While there are plenty of fun gameplay changes that should make the expansion better, one of the most interesting additions is that of choice. In an upcoming quest, players will be able to choose whether they want to support Saurfang or Sylvanas — essentially honor or evil — in the struggle for Horde warchief.