Sowmyag,
Sorry to hijack your thread, but sometimes I don't know which is the person's first name and which is their surname. I have colleagues all over the world, including many in India, Japan and other Asian countries. Often the only solution is to say "hi" or "hello", followed by the person's full name as they write it themselves. Once contact is established, I may feel bold enough to ask "By the way, what do you like to be called?"
I know that doesn't exactly answer your question but it may be useful on occasion.