When buying fins, what should I look for?

Must be rubber, or rubber-edged. Plastic fins are not allowed as these will injure other players. Just have a look at what other members use, and ask if you're not sure what to get. Prices will vary from £20-£60. Another good piece of kit to invest in is a pair of Fin-retainers (Like big rubber bands), for about £3 they prevent you losing a fin when you need it most!!