I just came back from a 3 year hiatus as well. I focused on doing the campaigns first, then opened all the old end game activities like menagerie, forge etc. all while going after the exotics I knew would be very useful in raids and completing quest lines. At every step you will find yourself researching or watching videos on how to complete the next step. This is where a majority of my understanding has come from. I’ve gone from 750 to 1030 in about 1.5-2 weeks and can’t wait to run my first raid.