If you are speaking to someone and you need to refer to them, THIS IS IMPORTANT!!
use their name, do not say you!!
お前: おまえ (you might hear this in the anime phrases, such as "omae wa mou shindeiru" or "you are already dead." DO NOT USE THIS, ever!)
あなた (this one is still slightly excepted, such as if you don't know their name, you may say あなた. otherwise just say the name if you know it, that is a thousand times more polite.)
EXAMPLE:
あなたは可愛い。(anata wa kawaii. you are cute) YOU DO NOT SAY THIS!! The correct, polite way is like this: name 可愛い。(kawaii) so if your name is sakura, its 桜さん可愛いです(sakurasan kawaii desu)
It's important to remember that in Japanese, to politely address someone you should use their name with a suffix or their title. The broad catch-all "you" words range mostly between overtly familiar and offensive, and require caution when used.