What are good profitable monsters to kill for an f2p player with 56 range and 38 defence

there aren't really many profitable monsters to kill in f2p. if you are not planning on training prayer, you can kill moss giants and sell the bones. you can kill cockroach soldiers for some ok cash but you should wait till you get higher def. you should try to get a longbow sight its a good item for training on high def monsters like cockroach soldiers or safe-spotting greater demons in wildy volcano.