First analyse your needs. You need protection from the cold, rain, wind, and sun. What materials are available? How long will you be needing shelter? You are in the forest. ( You shouldn’t be there without a good survival kit. It’s not like the city.) The more isolated you are, the more you have to rely on yourself. It’s going to get dark. You’re lost. Choose a location that is shielded from the wind as much as possible. Slightly higher than the surrounding area to drain any rain.
Build a frame from about one inch diameter poles. Cover these with evergreen boughs, weaving in between the poles. Have only one opening that you can cover once inside, if you can’t build a fire. You can also build a shelter with rocks if you are in an area where that is your only resource. Fill the cracks in with dirt to keep the wind out. The purpose of this shelter is to keep the wind and frost out, even if you can’t build a fire.
The wind will take your body heat away and you could suffer from hypothermia however your fitness levels will also affect this. One way to really build up your fitness levels is through pull-ups – here’s the best pull up bar if you need it.. Lay a bed of evergreen boughs about two inches deep for a mattress. Also cover yourself with these when it’s time to sleep. The main thing to consider is body temperature. You have to keep calm, conserve energy and don’t panic. Gather material for a fire. Dry moss, dry leaves, dead twigs. If it’s windy, you have to shelter the area that you are going to start the fire.
The important thing is to start the fire and keep it going. You can always move it to where you want later. In your survival kit you should have water proof matches, a steel and flint, and candles. To start a fire with sticks you need a base log about four inches diameter. A stick about three quarter inch diameter and about fourteen inches long. A rock that you place on top of the stick that allows the stick to rotate without slipping out. Take a shoelace and tie it to a branch to make a bow out of it. Loop the lace once around the three quarter stick and saw back and forth. Have your tinder ready. As the stick heats up, blow on it gently to give it oxygen. Once it starts to smolder, move the tinder close enough to catch on fire and blow gently to keep adding oxygen.