While exploring wilderness can be a wonderful, soul-enriching experience, it also has the potential to go drastically wrong if you are not properly prepared. Whenever you go into the wilderness, there are always certain things you should carry with you in case of an accident or an unplanned night out.
A good first aid kit is absolutely crucial when going into the wilderness. Prebuilt kits sold at stores, which usually have some small bandages and pain killers, are a good starting point, but there are several other items that can help. A SAM splint is a moldable splint that can be used to splint a broken arm, wrist or leg. Carry cling wrap of some sort, as well as 2-inch tape, to secure a splint in place. Cling wrap and tape can also be used to to secure bigger bandages. Carry a 3-by-3-inch or 4-by-4-inch bandage for bigger wounds. A bandanna can double as a sling for an injured arm.
Signaling and Navigation
Carry a map and compass, or a GPS unit of some sort, for navigation, especially if you get lost. If you do get lost, it is often best to stay put to maximize chances of being found. A signaling mirror and a whistle can be used to call for help to rescuers who are nearby, especially if you are injured and can't move. Carry a headlamp or small flashlight as well for signaling at a distance. Carry matches in a waterproof container to build a fire, both for warmth and to help in being spotted.
A good multi-tool, like a Leatherman, is indispensable. These tools usually have saws that can be used to cut wood, pliers, knife blades and screwdrivers that can be used for gear repair. Bring a water filter or iodine tables to treat any water, because dehydration can severely exacerbate wilderness emergencies.
Carry a space blanket with you, even on day hikes or snowshoeing trips. These blankets are very thermally efficient and can help ward off hypothermia, especially when supplemented with a hat.