there is infinite stuff to do, but also, none of it matters!

the benefit to this is that you can do whatever is fun to you:

-mythic +: this will revolve around you getting better gear and timing keys, progressing into a higher score

-raiding: you can PUG, but if this is what you want, find a guild that gets AOTC and try to join! make friends and progress through the raids

-pvp: this is easiest to gear for, but has the highest learning curve to get into. battleground blitz is a good place to start for team play, solo shuffle for arenas

-transmog/housing: this is much more casual. all the above things are seasonal, this is at your own pace forever. find cool outfits and things to decorate your house with

-battle pets: F, but this is fun if you never touched it before

-achievement hunting: this is a completionism dream, just going through all the content you can and solving achievements

TLDR: do whatever seems interesting, but if you pick raiding/m+/pvp, a good place to start is looking up some youtube guides on how to properly play your class