What: Choosing an Arabic heading typeface and body typeface whose visual weight and tone match.
Why: A harmonious pairing feels like one family; a clashing one scatters the eye and weakens identity.
How: Match x-height and visual weight, and make one distinctive for the heading and the other quiet for the body.
Common mistake: Combining a heavy heading font with a very thin body so they clash.
Exercise: Pair two Arabic typefaces in a heading and paragraph, tuning sizes until their presence balances.