Survive

According to experts, it´s very important that you know some easy tips that can help you in emergency situations and if you know them you can survive easier.
For example, if you are walking in the mountains and suddenly you get lost the worst thing that you can do is loose your calm. The first thing that you have to do is keep calm and stay where you are, because if you try to find the right way you can get lost even more and finally you´ll be exhausted.
Other important advice is that you have to ration your food and water because you do not know how many hours or days it will take them to find you. If you have to spend the night there, look for a safe place and make a fire to scare off animals because they can be dangerous.
Finally, you have to be very patient, sooner or later  they will find you, and losing your temper will only hurt you.

"Rationalise" in English means to explain a choice or a situation using reason. 

Survive

According to experts, it´s very important that you know some easy tips that can help you in emergency situations, and if you know it them* you can survive easier.
For example, is your are walking in a montain and suddenly you get lost, the worst thing that you can do is lost the calm panic^. The first thing that you have to do is keep calm is and stay where you are, because if you try to find the right way, you can get lost more more lost and finally you´d be exhausted.
Another important peice of advice is that you have to rationalize your food and water because you do not know how many hours or days it will take to find you. If you have to spend the night there, looking for a safe place and make a fire to scare off animals because they can be dangerous.
Finally, you have to be very patient, sooner or later you will be found, find and losing your temper will only hurt you.

*Them is used for plural nouns. It is used for singular nouns.

^We don't have a phrase for losing our ability to stay calm in English. Instead, we use the verb panic.