In general you should avoid to use あなた, and if you want to clarify the person whom you talk to just replace by the name. It might seem weird but that is the way. And useally you can omit the pronouns in conversation, like "What should I address you as?" =どう呼んだらいいですか?

I studied linguistics at university in Japan. According to the proffessor, there is not anyway to mention "you" politely in Japanese. Therefore, we should either ommit the subject or call him/her by the name.

I've hsard that teachers in language school tend to teach their student not to use "あなた" because it's rude. Well, I don't really think so. Look at Japanese textbooks. You'll find many あなた in it. That's incoherent. There are just some points: 1.During your work, you'd better try to remember for each person's name and call them their name. 2.We tend to avoid adding repeatly "わたし" or "あなた". 3.To repeat あなた so many times in a short time, it sounds unnatural or maybe overwhelmed. (If you think あなた is rude, is it because of that reason?) 4.There is no problem that you call your friend, lover or someone close to you. That is true that there are people who dislike that word, but people from other countries call someone あなた, it's not going to be any problem.

It totally depends on the YOU and the situation. Generally, it's said rude for your higher ranking person, such as your boss, but for example, when your wife calls you as あなた with sweet voice, it's so sweet. And when she calls あなた with violent voice, it's scared... How bad things did you do to her? lol. In the conversation, it's easy to know our feelings with tones. In writing, it's hard, so we likely use smileys. (^ ^) To avoid misunderstanding, we omit YOU very often. I would say すみません、おなまえは？ or あのーなんとおよびしたらいいですか？ すみません、えーっと、あのー help to make the words mild. Short and direct words are sometimes too strong. なまえは? is simple but rude to your boss. おなまえは？ is not so bad if you are a woman, but it's so weird if you are a man. It depends on the situation...