Before keeping secrets, it is best to understand whether the secret is a good or a bad one. A good secret is something that will make a person happy, for example, a surprise party for your mom on her birthday planned by you and your dad; it is OK to keep such good secrets. But, on the other hand, if the secret is creating a trouble to them or others, it is considered a bad secret. For example, a third person is buying you some chocolate and asking you to keep it a secret or someone is bullying or harassing you, and is threatening you to keeping it as a secret. Such bad secrets can cause you further troubles. It is always better to share these things to your parents and caretakers, before it creates a big issue. Do not get scared for any reason to share such secrets with them, as they love and trust you very much.
See Also: Whenever I feel unhappy or anxious, what should I do?