Wash the watermelon before cutting it. Due to its large size, you
will probably not be able to run it under water in the sink. Instead,
wash it with a wet cloth or paper towel.
Depending upon the size that you desire, there are many ways to cut a watermelon. The flesh can be sliced, cubed, or scooped into balls. Watermelon is delicious to eat as is, while it also makes a delightful addition to a fruit salad.
While many people are just accustomed to eating the juicy flesh
of the watermelon, both the seeds and the rind are also edible and
nutrient-rich. (In fact, in many parts of the world, watermelon seeds
are widely enjoyed as a snack and pickled watermelon rind has a rich
culinary tradition.) If you choose to eat the rind, we recommend
purchase of certified organic watermelon. (The reason for this
suggestion is an increased risk of unwanted contaminants like pesticide
residues on the outer skin of non-organic watermelon.)
By Source : http://www.whfoods.com/