Type Burrito spiega, semplicemente, per chi non ne capisce molto e si sente intimidito, come combinare e scegliere i font:
If you have two fonts that work together but still seem a little too similar, try changing the size or weight to add some variety.
Need more unity? The easiest place to start is to look at the shapes of the letterforms. Or try something more subtle and sophisticated: unify your typography by finding type designed around the same time, or to find type inspired by the same tool or medium (broad-nib pen, carved in stone, etc—you can usually figure this out with just a bit of googling).