How do scientists and anthropologists go about translating a new language?

Question

When some new language is found, say a new tribe of people were found in Africa that spoke no known language how would the people studying them go about translating what they are saying? Do they simply point at stuff, say what it is, and see what they say back?

Answer 1

there are a couple ways. they could look at its relations to similar languages. also, artifacts can be found that are translators; for example, the rosetta stone. it contained greek and hieroglyphic text that were translations of each other.  this enabled anthropologists how to read hieroglyphic.  

many ancient languages and writing systems have never been translated, for example the ancient civilization of the Indus valley.

Answer 2

I know when they found the Rosetta Stone and tried to translate the hieroglyphics, they referred to the most modern version of the ancient Egyptian language, called Coptic (which is still used in Egyptian Orthodox Church masses). This helped them understand the word order of the hieroglyphics, and how to decipher what the symbols would have sounded like back in ancient Egypt.

As for languages that are living, however - sure, they point and say stuff. Nouns and verbs are easy to learn, but more difficult concepts like adjectives and emotions take a bit more time. But essentially yes, that's how they learned the language. That, or they taught the natives how to speak English, and then had the natives teach them the language using English translations.