Also, don't forget the time differences when communicating.

When the sun is up here, in America, you should say "Konbanwa." But, once the sun sets, you should then say "Konnichiwa," indicating the different times of day.

Do note, however, that konnichiwa is a universal expression and can even be used at night, but it is more customary to use "konbanwa." Also, I've noticed that many Jpn players understand romaji, so if you don't have the JPN keyboard down, or the autowords ready, romaji will do. Many times I have had a conversation with JPN players in romaji. They still usually reply in Japanese, yet the conversation holds still.

Also:
Yoroshiku Onegaishimasu - nice to meet you. Something to say AFTER you finish playing with someone or meeting someone in PSO.