Astrological compatability.  'I'm a Gemini, you're a Capricorn - we don't get on'.  Utter drivel.  First and foremost, every chart therefore every person's tastes are different, there is no common factor.  But - here's some rules of thumb.  The sign opposite your Ascendant is often the one you get on best with.  The sign that Venus, and to a lesser extent Juno are in your chart show signs that you generally get on with.  The sign that Saturn is in your chart shows the sign you normally don't get on with, unless there's a multiple of a seven year gap between you.  And here's the secret weapon in synastry - if your Moons are in the same sign, you will feel the same things at the same time and enjoy similar experiences and sensations, and both go up and down in mood swings at the same time as each other.  Moon sign compatability is much more important than Sun sign compatability, because the Sun is about your individualty whereas the Moon shows how you get on with people at the emotional level.  UPDATE 16.45  Just watched the full Moon rising in the East, in the space of ten minutes it went from orange-rust through gold to yellow and now white...  I think the pubs, clubs, hospitals and police stations are going to be busy...  the sensible person stays in and has a private howl, there are nutters on the streets tonight.