Rinse the rice with cold water a few times, until the water turns clear. Drain the water.
Put the rinsed rice in a pot with water and bring to a boil. Turn the heat down and simmer for 20 minutes, or until the rice is cooked and most of the water is absorbed. The rice should be soft and "mushy". Make sure to stir the rice occasionally to keep it from sticking to the bottom of the pot.
Put the rice, along with 1/4 cup of water, into a Baby Bullet, food processor or blender. Blend until smooth. Add additional water, breast milk or formula to reach your desired consistency.
Mix spices of your choice into the rice cereal. I would suggest dividing the batch up and trying a couple of different spices such as cinnamon, ginger, allspice, and pumpkin spice.