A first-aid kit is one of the most important items among the 10 Essentials you should always bring when headed out on the trail. It is not intended to carry everything you could possibly need; rather, it should carry items that address common hiker maladies until you can make it back to your vehicle. While you can buy ready-made first-aid kits in stores, we recommend customizing them or even making your own. This ensures that you are familiar with its contents and have a basic understanding of how to use what is in it.