I too follow Greenstuff's method and it is simple.

I've used a knife method that I haven't found the slightest bit scary. In fact it's fun. Just hold the coconut in the palm of your hand, so that your thumb and little fingers are at the top and bottom.. Use the back side of a cleaver, and rap it on what would be the equator. Rotate, and keep rapping along the equator. Eventually, the coconut splits in half. There are lots of Youtube videos that demonstrate the method.