Most first ouds are bought online on the basis of how the rosette looks. Here is what actually matters.

The families

• Arabic (Egyptian, Syrian). Longer string length, around 61–62cm, lower tension, a deep and warm sound. Forgiving for a beginner and the most common reference point for the repertoire I play.
• Turkish. Shorter, around 58.5cm, tuned a whole tone higher, brighter and more responsive. Excellent for fast passages, less forgiving of a heavy hand.
• Iraqi. Often with an extra course and a distinct, resonant voice associated with the Baghdad school.

What to check before buying

The neck must be straight and the action low enough that the string meets the fingerboard cleanly at the octave. A high action on a fretless instrument is not a minor annoyance; it pulls the pitch sharp as you press, so your ear and your finger will disagree permanently.

Buy from someone who will set it up. A modest instrument that is properly adjusted beats an expensive one that arrives with the strings sitting three millimetres off the fingerboard, and a beginner cannot yet tell the difference by ear — only by how much their hand hurts after twenty minutes.