I doubt that there is one true path to playing TLS; this rings true especially for things like investments. However, two things seem to be universal to almost everyone's optimal playthrough: support the NUP rather than OZL, and have the succubi accepted instead of the church diverge or the new religion scenario.
However, with the release of Incubus War Aftermath, I think this certainity is no longer so certain. Supporting the OZL grants you the possibility of acquiring a Liquid Sex, while diverging the Church or creating a new religion provides massive benefits.
What do you all think?