Start with UV protection (look for UV400 or 100% UV), lens quality, and a comfortable fit. Check that the frame size and bridge width suit your face to avoid pinch or gaps.

Key factors are UV protection level, polarization (if glare is a concern), lens tint and color, and frame material for durability.

Nose pads, weight, and coating (anti-scratch or smudge resistance) affect long-wear comfort and lens cleanliness; also consider case and portability.

For bright sun, go for darker lenses or polarization; for commuting, a lightweight frame with a comfortable nose bridge; for daily wear, a versatile brown tone and comfortable fit are ideal.