For the eternal question of how to combine typefaces, contrast is often the answer. Look to pair fonts from different classifications, of different weights, or styles. Like Courrier International, this invitation by Nina Stössinger hits all three of those points. The card uses only two fonts: Bureau Grot Black, a heavy bludgeon of a sans, and Whitman, a serif with an elegant italic.
Nina achieved harmony between such opposites within the same paragraph by sizing the type so the x-heights matched. It also helps that, though Whitman was made in 2008, neither typeface is an ultra modern design. They feel like they come from similar eras.