I think the biggest thing for a "fun run" is experience with the game. You have to learn which scenes you can get that don't spike your addictions too quickly (or even ones that you can use to essentially skip any gains at all if you're looking for a more pure virgin run), and from there you can get scenes that let you spend time with at least all of the core 4 without destroying your chances to clear the endgame. With so many choices, it can be pretty easy to doom a run without knowing it, but you can still get certain addictions high without ruining your chances as long as you go for certain other scenes to outright avoid getting burned until the end. Certain addictions do make the endgame rough though, but sometimes you want to lose anyway to enjoy that content too.