While the sun is the best source for that ideal tan, do remember you shouldn't be freely exposed to it the entire day. You need to plan just how long you will be spending in the sun; remember, even your skin has a cut-off point where it will not be able to produce the tanning pigment known as melanin. Generally, two to three hours a day should suffice, though this can vary due to various factors such as skin type and colour, time of day and climate.