About Greetings

[mangiami.livejournal.com]

I remember being told that Russians only say Здравствуй(те) or Привет to each other once in a day, otherwise it sounds strange. I assume that's true, but correct me if it's just a regional thing or I'm just wrong. So, say that you see someone a lot in passing, like when going to different classes at a university, how would you greet them again?

Also, what are some conversation starting alternatives to Как дела? (Do Russians use that phrase as often as Americans say "How are you?") How do Russians normally start casual conversations?