Gather wood for the fire. You have to have enough tinder, kindling, and fuel wood. The wood should not be wet or live. Using wet or live materials for fire starting will result in more smoke than fire, so leaves should be avoided at all costs. To test whether the wood is good for fire or not, make sure that when you break the wood, it breaks cleanly. If the wood bends, it is not good for burning.
Clear the ground in a large circle where your fire will be. The circle should be at least a 2 meter circle away from trees.
Place rocks in a small circle in the center to make the fire ring. They should be big rocks, about 2-4 times larger than your fist. These will prevent the fire from spreading.
Place a large bed of tinder in the centre ready to take an ember.
Put a small amount of kindling in order to retain the flame once tinder is lit.
Find a suitable place to build. Generally, the best place to build a shelter is in a "fringe", an area between an open field and dense underbrush. Having water nearby is important, however the shelter should be built no less than 50 yards away or the water vapor might cause unwanted cooling of the area or flood unexpectedly.
Search for an object to brace the shelter against. Long boulders or fallen trees can be ideal for bracing a shelter, but any large, immobile object can work. It is also possible to tie a long branch between two other branches braced in the ground, though this can be more difficult and slightly less sturdy. Some people prefer to brace a sturdy, forked branch in the ground and lay a longer branch over the top. There are many different possible ways to build a lean-to.
Find sticks to lean against the horizontal brace. These sticks should be somewhat sturdy, as they will form a side of the shelter. Be sure that there is enough room between them and the brace for you to crawl inside comfortably.
Pile small branches and twigs over the stout sticks. Leave only the two ends open. These sticks will form the other side of the lean-to shelter.
Pile small debris such as leaves, grass, and moss over the frame. These will provide further insulation and protection from the elements. Nearly any small forest debris will work, so long as it won't blow away readily.