Use a colorful mixture of berries, i.e. blueberries, raspberries, black berries, strawberries. This can be any combination you choose. When purchasing check carefully; they should be firm yet ripe. They will be no good to you if they go to mush if you touch them, and they should be free of mold and insects. It is not recommended to keep them too long after purchasing. The berries should be gently washed before being cut.
