Answer:
Anata, Kimi, or Omae. The level of politeness is different but they're all "you". Although by all means if you know someone's name use that instead with "san" at the end. It is impolite to use you often.
You can be said many ways, depending on who you're talking to.
but if you want to be more polite, then you use kimitachi :)
Anata (formal)
Anta (informal)
Kimi (somewhat informal)
Omae, literally "My front" (very rude way of saying "you".)
One could add "Tachi" as a suffix to anata, "you" or watashi/boku, "me" neutral/masculine to make it plural, "you all" and "us"