P.S- sorry guys Taurus and Libra are the only sun signs I actually know about don't even know the names of the others or what ancient mumbo jumbo attributed them to.
Basically, you got four groups:
water: Cancer, Scorpio, Pisces - social types ("I gotta tell you about this 5D3 I bought!")
air: Gemini, Libra, Aquarius - cerebral types ("Let me tell you why I bought a 5D3!")
fire: Aries, Leo, Sagittarius - active types ("I bought a 5D3! I BOUGHT A 5D3!")
earth: Taurus, Virgo, Capricorn - down to earth types ("What do you care I have a 5D3?")
...and all that, of course, depending on in which of twelve celestial 'houses' or regions the sun was, when you were born. If you want more specifics, you can calculate where the moon and the planets were, so you have a nice set of zodiacal signs to explain your behaviour. Or, of course, you take responsibility for your own actions, but that seems to be less common.