There's no point in talking about sunscreen without reference to skin type. You're probably a Type 1, which doesn't tan in any significant way.

Anyone in the 2 and 3 range can build significant sun tolerance by being careful, 4 and 5s don't generally need sunscreen. Jury is out on skin cancer, Bantu people in Africa don't all die of melanoma, so clearly melanin is doing a lot of work here.