Can somebody help me with this problem...

I cannot get the clothes to fit correctly on my models.

for example i have poser 9

I have been trying to use jessie and apply one of her leotards to practice but her skin always pokes through. when I comform to her it forms her body in a weird position. If it has sleeves her forearms poke through the costume. 

I have done a new simulation and when I try to clotify the suit does not show up in the options. 

This happens with almost all the models. all the tutorials show the basics but they don't show my problems. 

Pease help.