What would you do in a situation you were not familiar with?

Depending what situation it was.

The most important thing before coming into a situation is to stand back and assess it. For example: An old man is at the side of the road with a stab wound on the side of his abdomen. You are an Excellent first aider and you can help him. The question is "Is it safe to do anything?"

It is likely that the the person who stabbed the old man may still be lurking somewhere and attack you. Therefore before approaching a situation, despite how well you know it, you should expect the unlikely.