hmm, if you want to be in character for
Ciel, like, he knows he's a guy, the audience who views him know there's more to him than a girl in a dress, etc etc etc.
i say to ALWAYS. i mean ALWAYS. tote a 'holier than thou' (lolironic?) look on your face.
stand with your posture straightened, practice holding an air of confidence (or something that seems that way) and just be, in general, cocky yet noble.
i always find that Ciel cosplayers tend to portray him nicely by tilting your head slightly up to the camera. yes, this is for regular Ciel, but this applies to his female version as well.
this is, though, if you are trying to be 'boy-trying-to-be-a-woman-but-failing-because-he's-too-rich-and-noble-for-this-stuff' Ciel.
in character for girl!Ciel when he was acting like a different person, try being a little bashful, and mock!modest.
i agree with adolf when they said generic elegant poses. i see a lot of female Ciels doing that.
... and stuff.
no pictures, i apologize.