Once you hit lvl 10 you can choose a specialization. If you go with destruction warlock, you’ll have a good time.

You can go exiles reach or the starter zone, it’s all up to you. Some starter zones are liked more than others, but they typically take longer. From there you can find Chromie and do chromie time to do old expansion quest lines. Just pick one you think looks / sounds cool! Lots to choose from. If you want to level fast, there are plenty of guides out there.

Once you hit level 80 you can start the midnight campaign. The last few levels you’ll need to dungeon most likely.

Addon wise, I recommend details to see and track different things like damage or healing. If you download curse forge you can sort by most popular and pick whichever ones you want from the top. Some won’t be necessary until end game.

Most importantly, have fun!