cleaning_sunglasses

That is the easy part. The hard part is getting them adequately clean without scratching the surface, risking some sort of other damage, or taking a bunch of time.
NORMAL CLEANING
To dampen or not to dampen? That is the question. For most of us, dirty glasses means a light coating of mostly just fingerprints and other light dust and smudges. This type of dirtiness is super easy to clean using just a DRY lens cloth. If the dirt was a little more stubborn, or if there was more of it, then you will want to get the cloth DAMP. A dry lens cloth will do the job in most cases, for most people, but if it is not quite getting everything off, simply get your cloth damp under the tap, and it will increase the cleaning power. You could also lightly wet the lenses directly using a spray bottle, or by sticking them under the faucet. This will add moisture, but allow you to keep the cloth dry. With a damp cloth or lens, you will be able to power through any stuck on goo or greasy smudges with ease and there will never be any additional chemical sprays, special steps, or fancy tools necessary. The whole job should only take a couple minutes at the most.