Start with the watermelon on the cutting board. Slice off a thin part of each end. Try not to cut too deep into the red flesh, as this is the product you will eat.
Once you have both ends sliced, stand the watermelon up on one end.
Start by cutting from the top of the melon to the bottom, trying to keep your knife just on the white part and not cutting into the red flesh. As you cut, you will follow the natural curve of the rind to the bottom.
Cut the watermelon into thick slices, ½-1 inch, depending on your preference. After that, trim the edges to square the slices off.
Once you have the slices, cut them vertically into large, rectangular pieces. Once you are done with that, turn the sheet of melon and cut vertically again to create uniform squares.
Store in an airtight container in the fridge and enjoy.