I've seen a lot of people saying that First Learners should be careful when greeting a Japanese. I have to be careful how to address Japanese people with '-Chan', '-Kun', '-San' and '-Sama' and also how to refer them. I noticed that it would be hard for me to greet a Japanese properly in our first meeting since I don't know her/his name.
Out of curiosity, is it informal to greet Japanese strangers with 'Ohayo', 'Konnichiwa', or 'Konbanwa' only when I go around and see one?
If this question seems inappropriate or stupid, I apologize for my curiosity.