Final answer:
Vittorio should clean the dusty mirror using a clean, soft microfiber cloth, dampened with a cleaning solution, and wiping in one direction to avoid scratching the mirror's surface with debris collected on the cloth.
Step-by-step explanation:
When dealing with the cleaning of a dusty mirror, it is important to be aware of how to handle delicate optical surfaces. Cleaning your camera lens or a mirror is similar in that you should avoid wiping dirt directly on the surface as it can scratch it. For Vittorio to clean the mirror while cleaning as little as possible, he would need to use a clean, soft cloth, preferably microfiber, slightly dampened with a suitable cleaning solution, and gently wipe the mirror in one direction without reusing the same part of the cloth. This is because the dust and debris collected on the cloth from the initial wipe could potentially scratch the mirror if reused.