Shadowlands has a lot of new systems that hit you when you hit 60, and it’s not entirely clear at first what you have to do and how the systems interact. This “guide” is for the people who don’t have much time for the game, hit max level and wonder what to do.
First some generalizations: if you have just leveled up and want to raid, then the gearing is basically the same as previous expansions. Start with normal dungeons, gear up to do heroics, and then mythics. You can shorten this process by asking in guild, quite often people will take you through content you aren’t really ready for yet. There are crafted pieces that can get make normal dungeons easier, but you’ll replace them in heroic dungeons. For reference, in order to use the Blizzard queue for heroic dungeons, you need to be an average item level (ilvl) of 155. Mythics drop 184 gear. The normal raid drops ilvl 200 gear. As a rule of thumb, your gear can be 15 ilvls lower than the gear that’s dropped by what you’re trying to do, and you won’t die too much. )
There are a few other sources of gear that can contribute a couple of pieces. The significant one is the Legendary Item system, more on that at the link. Other sources include world quests, Adventure Table(link), covenant story line, and some treasures.
There are a lot of different factions each with their own reputation line. However, the items you get from those reputations are mainly cosmetic, pets/mounts, or crafting recipes. They don’t have anything that is necessary for doing some content. There are a few pieces of purchasable gear, generally 1 piece in the normal-heroic dungeon range and one (at exalted) in the epic range.
The main new system in Shadowlands is the Covenant(link), and that does affect your character’s power in a couple of ways. When you hit 60 you choose a covenant; that’s the first step on the chain leading you through all the different systems. Now, one thing I’d wished I’d know—when Tal-Inara says to talk to the different covenant representatives there in Oribos, she means it. I knew which covenant I wanted, but still had to go talk to each one before I was allowed to pick. The powers conferred by the covenants are pretty close in effectiveness; I would choose based on what you liked about them as you were leveling up. If you later change your mind you can change to a new one.
Covenants don’t have reputation, they have Renown. Each renown level is a chapter in the story of the Covenant, and it’s very clear which quests they offer give a renown level and which don’t. There are 40 renown levels, but everyone throughout the game is restricted in how high a renown they can have. This week is 18, it goes up 3 per week. If you’re just starting out, you can get lots of renown in a week from catch-up mechanics, so you are not permanently behind.
At certain renown levels, the ilvl of the rewards from world quests or pvp items increase. At others, the number of Soulbind (see Covenants link) choices increases. And at some points you get story quests that advance the story of the covenants, which are different for each covenant. Some renown levels are not very interesting (e.g. 2% stamina), but that’s life.
Every covenant gives you two powers when you join them (there’s a quest chain in each one on joining them). One of the powers is meant to be combat useful, the other is not. You probably still want to find room for both of them on your bar. They are the same two powers you got to try out when you followed through the story of the zone while leveling. Each covenant also gives you some minor advantages in the dungeons that are located in that zone.
Joining the covenant has an introductory quest that kind of shows you around and gets you started. After that, they will send you back into the Maw (link), and the chain will continue with Ve'nari (link) and Torghast (link).
Once you’ve been through the Maw and Torghast once, so you know where they are, lots of quests open up and attempt to overwhelm you. Do what interests you and you find fun; I recommend doing enough to build a legendary and follow any story bits that Bolvar (link) has for you.
Tl;dr. Each week do the quest to get souls from the Maw for your Covenant, and as many of the other quests that award renown that you have time for. Do as much Torghast as you have to in order to build your Legendary. If you’re looking for gear, do dungeons. Play what you want.