How does one use watercolor pencils?

I've never heard of water soluble oil pastels. I work with water soluble oils, and I have tried oil pastels but don't use them on a regular basis. I can research this for you and hopefully give you a better answer soon. Update. I found a great deal of information on WetCanvas.com in their oil pastel forum. You may want to check there for more detailed. Basically you can just apply water to blend out the color instead of turps like you would with regular oil pastels. You can apply it dry and just layer it, or wet it to give a watercolor effect. You can also wet the surface and then apply it. Experimentation is the key. The related link will give you more detail