>>2742421First, you need protection fdom the elements. Severe weather will kill you within hours. That means wearing the right clothes and finding (or building) shelter.
Next, you want to find a way to be rescued. That means trying to communicate with the outside world. If you can't you want to make yourself (your location) as visible as possible. That means, fire, smoke, bright/contrasting colours, big SOS in the sand, whatever makes you stand out for aircraft or satelites searching for you. Think BIG.
Then, you need to be able to make a fire, so it's worth building your fire skills beforehand. Petrol and a lighter is low-tier skill. Fire-by-friction (rubbing sticks together) is yoda-tier skills. With fire you can stay warm, make signals to get rescued, boil water for drinking, cook food and protect yourself from wildlife etc etc.
Then you need to find a water source and a way to collect, filter and purify the water, if required.
Eventually you'll also need to find food but this can really wait until you've got the other stuff sorted. In this particular survival case, the people took to canibalism to survive. Canabalism is actually a realistic option if there is no other food source. The main problem with it is the psychological effect it has on people.
Finally, a useful guide is the rule of 3:
3 hours without shelter, you'll die.
3 days without water, you'll die.
3 weeks without food, you'll die.
3 months without hope, you'll give up and die.
Of course all these things vary, depending on your environment (snow, desert, jungle etc)
>t. survivalist ninja 
