I'm big into astrology.Since Yu Yu Hakusho is a series that doesn't put much details on the characters personal info, I decided to base the characters' zodiac sign on their personality.
So far my conclusion.
Yusuke-Pisces.He definitely is a classic Pisces minus the extreme escapism and depression. I could explain so much about how he is Piscean in nature that it would be worthy of its own thread. Plus I'm a classic Pisces so I should know.But just a bit of summary, start of the series he was really such a lazy slacker who gave up on everything when the going gets tough (unless his loved ones were in danger). He is such an emotional person who cries so many times throughout the series and how he becomes much more motivated and determined when his loved ones are on the line is definitely Piscean. He shows the duality of the Pisces twin fish in that he has a reputation of being a bad punk and is generally shunned and hated by most students and teachers but deep inside he has such a heart of gold. And lastly, by the Three Kings Arc, he gets such a feeling of emptiness despite the fact that there is no reason to be that way as he now had a good life and the world was at peace at the start of the arc.Typical Pisces feeling of lack of direction in life.
Not to mention Puu, his inner beast, being so sweet as opposed to Yusuke's badboy obnoxious attitude portrays the Piscean Duality even more.
Kurama-Capricorn. Definitely!Not only does he show the maturity and bookwormish nature of Capricorn <3, IIRC in the Yu Yu Hakusho wiki it stated that the latest releases state Kurama is born on December 29! So definitely a sure Capricorn here!
Kuwabara-Sagittairius. Oh good lord. How he such a strong code of honor and honesty. Plus he becomes a scientist later (scholarly nature of Sagittarians).
Hiei-Cancer. Very much. The most violent of the entire cast who enjoys killing for the sake of it. However his attitude to Yukina is such a caring and motherly one. How he constantly keeps an eye on her because he's concerned for her welfare. Plus later he really does become so caring of Team Urameshi's members.Then there is his affection for Mukoro. Definitely Cancer here.
Keiko-Aqaurius. I don't really know much about the Aqaurius sign but her personality does matches what I've read online with how she is bossy around Yusuke and tries to control him for his welfare. Plus she's born in January 31 so she is definitely an Aqaurius by birthdate.
To be frightfully honest though I do tend to like to think Keiko as being Capricorn. I mean his relationship with Yusuke is so typical of a Pisces man-Capricorn girl relationship !!!!!!! Plus she's so mature and such a bookish girl. I don't know Keiko has so many traits of my ideal girl and indeed those same traits are Capricornish. I just really do have a knack for Capricorns .
Botan-I tend to liken her as a Scorpio. I mean she's so witty and intelligent! Such a live girl to be with and at times when she's all pumped up she's fiery!Not to mention when she loses her temper she can be very Scorpioish minus the scary violence tantrum Scorpio girls are renown for .
More to be added later! Post your interpretations!