Jewelry should be taken care of better than we actually do (I am guilty of this myself). It shouldn't be exposed to make up, sprays, perfumes, soap & lotions as the plating can be worn off. It is recommended that you take your jewelry off to swim, shower, and sleep. When you are not wearing your sterling silver or silver plated jewelry you should store it in an air tight zip-lock bag - this will help.
If your jewelry does tarnish you can always gently scrub it off with an old toothbrush and toothpaste then rinse with water but dry thoroughly immediately afterwards.
LASER ENGRAVED CHARMS:
Remove protective covering on the charm; clean any packaging residue with a lint free soft cloth and vinegar.