a) Once I get a tan I don’t need to use sun protection anymore. Tanning is an injury response of the skin to sun exposure. Some people tan very easily but still benefit from using sun protection.
b) I have very dark skin and therefore can’t get skin cancer. All skin types from fair (eg. light Irish skin) to dark (eg. African American) can get sun related skin cancer. It is true that in general the darker the skin type the smaller the incidence of skin cancer.
c) Skin cancer only occurs from sun exposure. Skin cancer occurs on both sun exposed as well as sun protected areas. Sun protected areas as an adult might have seen a lot of sun when the adult was younger but also it can occur where the sun never shined (eg buttocks and bottom of the feet). In fact the most common location for a melanoma in a black skinned individual is on the hands and feet (acral lentiginous melanoma)
d) once you get a skin cancer you should not go in the sun anymore. Not true. Life is short and people should use sun protective measures (clothing and sunscreens) but doing the fun stuff in life (eg golf) is ok.