In most everyone’s attic or storage space lurks a box. Inside this box is a ball of impenetrably knotted strings of LED Christmas tree lights, the green electrical cords folding in on themselves. Even after untangling it, you still might find you have too few strings for your tree, or possibly way too many. According to Real Simple, there’s an easy way to calculate how much string lighting is needed for any size Christmas tree. You’ll get a bright, colorful look by adding one strand per foot of tree. (Bulb count can vary by brand, but many strands have around 150 lights.) If you have a typical 6-foot tree, you’d want six strands for coverage, with two additional strands on standby to fill any gaps. If you prefer a tree that’s more densely populated with light, you don’t necessarily need to add more strands—just buy some with more bulbs per strand. To decorate a tree, start the first strand nearest a wall outlet and encircle the trunk. You can secure lights on lighter branches with floral wire. After the holidays, you can use twist ties to store the lights in some semblance of order. That way, you’ll always have the right amount of lighting—tangle-free. In New England, it’s...