Tim Brown, a former colleague and a great friend of mine, had written a little book called Combining Typefaces. Even though the text is quite short, Tim managed to squeeze in invaluable resources for readers to explore further. The e-book format turns out to be quite useful for that task.
One of the advices I take away from the book is to experiment with different types. Nothing wrong with sticking to just one family, “But it also robs us of the opportunity to truly understand why a combination works or doesn’t, and can lead to a false sense of completion.” Tim said, “The task of combining typefaces doesn’t begin or end with any single piece of advice—it is necessarily more complex, and dependent upon a project’s design goals.” I’ll definitely keep that mind when designing my next project.