Full foot fins are sized according to your normal shoe size. Your feet should fit the fins snugly, not too tight or too loose. On some models where sizing of the fin is across several sizes (38.5-39.5 ::8.5-9.5 for example), your toes may or may not stick out from the end of the foot pocket.
Adjustable heel fins are sized in bands, but not all manufacturers use the same bands or descriptions. For example one manufacturer may call a fin size regular and another may call it medium, although both refer to the same actual size. When you try these style of fins on, you should do so with your boots. Your ankle should be approximately in line with the very back of the bottom of the fin foot pocket.
Fins are available in a variety of colours. It's a good idea to go for bright ones so that you can be seen easily underwater. Of course you can match your fins with the rest of your gear if required.
Contrary to popular myths, there are no colours that are guaranteed to attract sealife species!
