If you didn't catch the first post about Susan you'll want to read here first.
Final step. Get some clay tools, wood carving tools, turpentine and paintbrushes.
Remove "strategic" areas of ink and oil pastel from the surface of your inked oil pastels. The pressure you exert will determine the depth at which you reveal color.
A.) Push light and reveal the oil pastel.
B.) Press hard and reveal the stained paper.
C.) Don't press at all and leaved the stained inked oil pastel. Usually good for shadow.
Go over the work with a paintbrush dipped in turpentine to smooth out areas. The bristles and turpentine will blend color and pull away oil pastel. A brush works great on the dark areas in order sharpen areas, and smooth harsh areas you went over with wood carving or clay tools.
REMEMBER when you're doing this the key is diluting the etching ink as thin as you can so you cast a hue, not darkness. You want the etching ink to alter the colors, which are preserved beneath the surface, and you will reveal with your tools.
Enjoy the beauty of layers!