Protective case: Always use a hard or semi-hard case to store your sunglasses when you are not wearing them. This will help prevent scratches and damage when you store them in your bag, backpack or towel.
Proper cleaning: Clean your sunglasses with a soft, clean microfiber cloth. Avoid using toilet paper, napkins, or other rough materials that can scratch the lenses. If the glasses are very dirty, rinse them with fresh water first before cleaning.
Rinse with fresh water: After being at the beach, rinse your sunglasses with fresh water to remove salt and sand. This is especially important if the glasses have been wet with sea water, as salt can damage coatings and frames.
Avoid prolonged exposure to direct sunlight: When not wearing your sunglasses, store them in a shaded area or in their case to avoid prolonged exposure to direct sunlight. Intense sunlight and heat can affect lens coatings and warp frames.
UV Protection: Make sure your sunglasses have adequate UV protection to protect your eyes from harmful ultraviolet rays. Check the label or product description before purchasing.
Avoid leaving them face down: Don't place your sunglasses upside down, as this could scratch the lenses. If you do leave them on a surface, place them with the lenses facing up.
Don't put them on your head: Avoid using your sunglasses as a headband, as this can stretch the temples and cause the frames to become misaligned over time.
Do not leave them in hot places: Avoid leaving your sunglasses on a hot car dashboard or anywhere where they will be exposed to high temperatures, as excessive heat can damage the frames and lens coatings.