I use a large chef's knife. I insert the point of the knife into one end and exert pressure on it while kind-of rocking it back and forth to cut through the skin. If the squash is a large one (like I'm apt to buy, especially for holiday meals), it will probably only cut part of the way before it becomes stuck; you then put yourself in reverse -- hold the squash down and rock the knife back and forth while you pull on it to get it out. Wipe blood off vegetable, get a bandaid and continue. Now, turn the squash upside down, insert the point into the skin on this side, and rocking the knife back and forth, try to meet up with your original cut.