Yes, we know this is a bonehead basic, but recommending a flashlight as an essential is our way of saying that sometimes the best tools are the old standbys you forget to take with you when you have a small job to do. Whether it's in the basement, in the back of a cabinet, behind the refrigerator or under the sink, light is important and often unavailable in tight, cobwebby and little used spaces. Always keep a flashlight handy, and have replacement batteries at the ready. This is important for emergencies like power outages, too. In fact, have a variety of flashlights on hand. From floodlights to penlights, sooner or later you'll use them all.