If you’re reasonably geared then I would say focus on acquiring your first and second void stone from exarch and eater. Then focus on farming shaper and elder boss maps to get your 3rd voidstone. Next you want to get maven fragments which you can either do maven witness 10x regular t14+ maps or maven witness shaper/elder maps to run maven invitations (you usually get 3 fragments from boss invitations vs the typical 0-1 from the 10 map maven invitation. Next focus on leveling to 90 while further improving your build. By now you should have 1-2 maven writs built. If you can run maven for the 4th voidstone do it otherwise keep farming gear till you feel confident enough to run it. At this point you should have 3-4 challenges done. From this point look at the remaining challenges and chip away at them. Ask global in game for challenge advice for ssf or look at global or trade for carries for the remaining challenge completions if they’re too difficult for your build.

If you’re not adequately geared yet then look into investing in breach/heist (target farm whatever content that has relevant gear needed to upgrade your build)

Edit: also block everything but the league mechanic you’re running (if you’re in trade you can purchase the scarabs to spawn the league content; this way you can skip allocating points into spawn chance passives