In general, sign language is grouped into three sections :
Deaf sign languages: The preferred languages of Deaf communities around the world; including village sign languages, shared with the hearing community, and Deaf-community sign languages
Auxiliary sign languages: Sign systems used alongside oral, spoken languages.
Signed modes of spoken languages, or manually coded languages: Used to bridge signed and spoken languages
I never teach friends sign language, but I used to learn some years ago in order to communicate with people inside my company. I think flexibility in your communication and different languages is very important in daily basis. if you like to teach people to learn this language or just want to learn to have great times with different people, I really support you in your decision. Have a great life.