Contrast 

Contrast in combining typefaces can be tricky. Too little contrast can make fonts clash, while too much contrast can do the same. 

Contrast when combining fonts refers to any way in which the fonts are different, including classification, weight, style, and structure. 

When starting out, it’s best to focus on the contrast between only one or two of those things, while making sure the others are very similar. Weight is one of the easiest ways to create contrast between fonts. As already mentioned, too much contrast in weight can be just as jarring as too little. 

Another easy way to create contrast is by combining different classifications of fonts, such as sans serif and serif or script and serif, etc. In these cases, making sure the mood of the two fonts matches up is essential. 

For example, combining a more casual font like Amatic SC with a very formal font like Baskerville will clash rather than contrast. But combining something like Amatic SC with another casual font like Josefin Slab works beautifully. 

X-Height 

X-height refers to the height of individual characters within a typeface, specifically the lowercase x. Typefaces with similar x-heights will work better together than those with varying x-heights.