I was a Peace Corps volunteer in Togo from 1985 to 1987. Here is a short list of things I learned then that have been helpful to me in doing linguistic fieldwork ever since (especially in Togo, Namibia and Botswana).
1. How to live without electricity.
2. How to live in a rural village.
3. The importance of greeting people.
4. How to live with goats and chickens walking around.
5. How to learn a language as an adult outside of the classroom.
6. How to eat corn porridge.
7. How to cope with learning two languages at the same time.
8. How to live alone in a very different culture without cracking.
9. How to bargain.
10. How to take a bucket shower.