DON’T ... ask for a Christian name or surname. Ask for their first, personal or family name instead. And don’t assume that a response to questions in English means that the person fully understands what you are saying.
DON’T ... assume that not keeping eye contact in conversation is a sign of dishonesty or disrespect. In some communities, the opposite applies. And don’t assume that just because voices are raised that a person is losing control or becoming aggressive. In some communities, it is common practice for people to speak loudly and to be animated with their bodies and their sense of personal space can be much less than your own.