Think about the photo before and after, never during. The secret is to take your time. You mustn't go too fast. The subject must forget about you. Then, however, you must be very quick.
Henri Cartier-Bresson
I love moss and have tried a few of these shots myself. The low angle you choose makes depth of field really a big factor, which is why only a small area at the centre of the moss is nicely sharp. You can fix this one of two ways, use a tripod and a smaller aperture and longer exposure, the smaller ap will give you a deeper area that is in focus. Or you can position yourself more squarely on to your moss so it's all in the one plane of focus. Good luck.