We have several ways for the formarity of speak. あなたのおなまえはなんですか is correct, and asking so has no problem for learners. However, since I am Japanese, I would say: おなまえをおしえてください。 おなまえをおしえていただけますか。 (like "may I have your name?" ) I hope this was helpful.

Vatasi no namae va nan des ka?

あなた (anata) is a little too direct, especially when meeting people for the first time. You rarely hear it with the exception of a wife calling her husband. お名前は？(o-namae wa?) is perfectly acceptable.

あなたのお名前は何ですか？ (anata no onamae wa nandesuka?) This one is a pretty direct way of asking and could be considered rude. You can skip the 'anata' part if you want and simply ask: お名前は何ですか？ (onamae wa nandesuka?) It should be pretty clear that you're asking about their name, so you don't need to add the 'anata'. 'anata' basically means you. 'namae' means name. You add o before it to make it more polite. 'nani' means what, 'desu' is a polite sentence ender that means is or to be. 'ka' at the end of a sentence makes the sentence into a question.