What is the proper way to say hello in Japanese?

This might sound like a stupid question but at first i knew hello was "Konnichiwa" but then i heard that if you say konnichiwa to somebody at 8 in the morning they'll look at you strangely. Should it be Ohaiyo in the morning, Konnichiwa in the afternoon, and Konban wa(sorry if i didn't spell that right) in the evening? or just be Konnichiwa all day?