If you’re often searching for that elusive Band-Aid while trying to keep your freshly cut finger from bleeding, it’s time to assemble a first-aid kit. Having supplies in one well-stocked bag can help you better respond to injuries and emergencies. You’ll need: How-to manual. Should you ice a burn? Bandage a sprain snugly? You could Google what to do, but it helps to have a paper guide handy. Download a free manual from the American College of Emergency Physicians, or purchase a guide from the American Red Cross. The answers, by the way, are no and no: It’s cool water …