Clean them gently!
Wipe your lenses regularly using a special micro-fibre cloth. If the stains are stubborn, wash your eyeglasses using lukewarm water and a mild soap, then rinse them with clean water.
Dry them with a soft, smooth cloth. Avoid using any cloth or paper not designed for glasses: paper towel, shirts, ties, etc. And never use a cleaner with an ammonia base.
Have them adjusted by a professional!
If your frames need adjusting because they were dropped or twisted inadvertently, take them to an eyecare professional, who has the tools and the training to make any adjustments properly.
Two times per year, take your eyeglasses in for deep cleaning in an ultrasound bath.
Store and handle them with care!
Always set your eyeglasses down with the lenses facing up, to avoid direct contact between the lenses and a surface. It's an easy way to avoid scratches.
Keep your eyeglasses in their case, which protects them against shocks and scratches. To remove your eyeglasses from their case, grab the glasses by the centre of the frame, where the nose sits.
Take your eyeglasses off carefully, with both hands, to avoid twisting the frames.
Keep your eyeglasses away from sources of heat: ophthalmic lenses can easily be damaged by exposure to high heat, like home heaters, radiators, the stove or the dashboard of your car.