I think that is one golden rule a man should never 'tell' what a woman should wear unless he's a fashionista himself lol. May I ask how old she is? And the theme of the photoshot? How to approach her? Causal yet professional, and since your doing a CD cover and the insides of it find out what sort of look she wants to achieve. Then ask her if she knows what she would like to wear. You also said that black and white or highley patterned is out, so does that apply to the whole outfit? or are those definately out? And doing this over the phone might be tricky, so maybe you can suggest to her bringing the outfits she had in mind and doing some test shots?