It may not seem like it but finding models in these poses is rare. The pose should be knees together, sitting up and eyes into the camera. Attitude is a big component for these photos. The models should have a "come hither" look in their eyes. Almost as if she was about to take you over her knees for a playful or not so playful spanking. Nude or clothed is fine - please help me find more. (Note: Women posed sitting on their knees or spreading for the camera is not appropriate. Those poses are very common plentiful and easily found.)
eighties private model nadine: http://fotoalbum.web.de/gast/nadine
http://timdir.com/hayley_hanes_tie_stockings/