Outdoor necessities include a compass, first aid kit, a whistle and mirror for signaling, space blanket, and a detailed map of the area. Familiarize yourself with the area before you enter, and take someone with you who knows the area. Always be specific with friends or relative about your planned route and stick to it. IF YOU GET LOST. . . Especially at night.
Stationary people are much easier to find.
The mountains are more rugged and difficult a climb than most people realize. Before attempting snow field climbing, get adequate training in the use of crampons and snowshoes. And again be specific with your plans and route. Tell somebody where and how you plan to climb, and what day and time or your return. It takes only a moment to sign the Trailhead register, but that information may save your life.