Don't lose heart.
Once you start with effects like split toning, you are metaphorically in the "wild west" where rules are largely out the window and experimentation is about the only rule intact. Tim Rudman's book on toning is excellent and helps lay out something of a "map" of the wild west. Many surprising routes are explained - such as going back into developer - !after toning in some toners! I learned a great deal from the book.
It's probably best to use quite a bunch of prints as test platforms to get hold of the process before you expect dependable results from advanced toning techniques.