Overall, I agree with all of the comments that say you should leave a lot to the readers own imagination. However, you can not let the reader stagger too blindly. Who knows what mischief they might get themselves into.
For myself, I like to give a sketch, elaborating on background a little, but I will also try to add hints as to their personality (EG She was also quite rare in that, unlike other girls of her age group, she was still comfortable to wear her hair in plats.). I think that what I am saying is that it is best to give the reader a general outline, where you also hint at the emotional charactor, rather than the usual hair colour, vital statistics and job description (At 24, Cherry considered her looks to be one of her best assets. Although she was quite a successful lawyer and enjoyed the power that this career choice gave her amongst her fellows, long blond hair, a 24" waist and 34DD breasts gave her an even greater advantage, in and out of court, Blah, Blah, Blah).
Rubberwolf