A photography instructor once told me that “You have to know the rules before you can break them.”
That’s the (simultaneously frustrating and freeing) thing about art and design — there may be some rules; there may be some best practices; but there are very few that are set in stone. Bending or breaking the rules is always a possibility in the right context. So how do we go about learning how to effectively combine fonts? By looking a few guidelines, we can see what has proven to work well as a starting point, then get comfortable moving beyond those basics if a design calls for it.