For perfect rice, follow the ideal water-to-rice ratio. Typically, for white rice, use 1 cup of rice to 2 cups of water.
If you like the rice to be more moist, use a 1: 2 ratio instead. Put a measure of rice (say, two cups) into a bowl. Add water to cover by about 2.5cm (1 inch), stir well, then pour off the water.