Konnichi wa

Hhajimemashite, watashi wa Amanda desu. Yoroshiku onegaishimasu. Onamae wa?

I think it's perfect :)
I dare to say "Anata no onamae wa nan desu ka?" is more polite expression I think.
I have another expression at the same situation.
"(Anata no) onamae wo oukagai shitemo ii desu ka?"
I use this phrase for my work.

Ganbatte kudasai!

:)