Need tips for getting back into wow

[neotheone]

With the whole quarantine situation my classes have effectively cancelled all their work and I was laid off from my job so naturally I will once again feed my crippling wow addiction to pass the time. I am coming back from a years long break (ish) and all the systems are now foreign to me and I'm not really sure where to start. Essences seem pretty important so ill be going for the best ones for my class (DK) but from what I can tell the higher end ones seem to be in areas that require at least decent gear. I've done all (i think) the intro quests to the new content but am struggling to find the most efficient way to gear. Any recommendations for essence farming and gearing would be great. Are there important breakpoints for the the heart of Azeroth that I should look to hit or is it just kinda bonus stats that you don't need? Any tips would be greatly appreciated and thanks in advance!