>>535760508
The VN doesn't really punish you too heavily for your choices, just save semi-regularly and you're fine.

If you mean what to do after the VN, I would recommend either Fate/Hollow Ataraxia Remastered (which just released on PC and consoles this month) or Fate/Zero (light novels that have been adapted to anime). HA is a sort-of sequel and Zero is a prequel.

Once you're done with those you can kind of just experiment with the franchise however you want as everything else (Apocrypha, Grand Order, etc.) is spin offs with the same concepts but different continuities.