Apple has posted an article on how to clean your Apple products. These guidelines apply to all brands of technology, not just Apple products.

• Use only a soft, lint-free cloth. Avoid abrasive cloths, towels, paper towels, or similar items. 
• Avoid excessive wiping, which might cause damage. 
• Unplug all external power sources, devices, and cables.
• Keep liquids away from the product, unless otherwise noted for specific products.
• Don't get moisture into any openings.
• Don't use aerosol sprays, bleaches, or abrasives.
• Don't spray cleaners directly onto the item.

The full article is available here: https://support.apple.com/en-us/HT204172