In survival situations I prioritize my needs in this order: shelter, water, fire, food.
If we take a look at how long we can live without each of those things we see that in severe situations we might only live up to three hours without shelter, three days without water, and three weeks with out food. You see that fire is the third priority; there is flexibility in when to make a fire depending on your situation. Generally speaking shelter and water are more important then fire – however you might need the fire for your shelter, or to help purify water – in which case you make a fire sooner.
Once I decide I’m in a survival situation, I look to see what resources are around me. I begin with a look for natural shelters; a hollow log, an overhang, thick brush, or a dense tree grouping. I also look for materials to insulate with; leaves, grasses, ferns, and even moss if it is dry.
One misconception I used to have about these survival priorities is that I had to focus only on shelter, then water, then fire, then food. This has looked like spending all day only building a shelter, and at the end of the day I am exhausted, grumpy, and have a headache from not having any water or food all day. From my own experiences I have learned to work towards all of these survival priorities at the same time. While I am looking for a shelter site and materials I am also keeping an eye out for a water source. I am keeping an eye out for dried materials to start a fire, specifically I put tinder material in my pocket as I find it. And I am keeping an eye out for edible and medicinal plants, and the tracks and signs of animals.
Now, by the time I decide on a shelter location; I have a pocket with tinder in it, and other materials for starting a fire; I have an idea about what my water source will be; I’ve eaten a few edible plants and maybe harvested some for later. By the end of that day I have a shelter built, a fire going if I need to boil my water, and edible plants and maybe some insects for dinner. I can go to bed happy and with something in my stomach!