Use the tip of the oil pastels to draw thin lines and details on your paper. Fill larger areas with solid color using the sides of the pastels.
Vary the pressure of your strokes according to the effects you want to obtain. If you press hard on the paper, you obtain a thick color, but pay attention not to damage the paper or break the color sticks. Draw a few dots and rub the paper with your fingers or with a piece of cloth to obtain a more transparent color.
Obtain washes by applying a few drops of turpentine or paint thinner on the oil pastel color. Use a paintbrush to spread the color or mix the color with another one. This technique gives you effects that are similar to watercolor paintings. The paper is fragile while wet, so allow it to dry before you use other colors. Alternate washes with areas with solid colors to obtain various effects. Don't use water on oil pastels. If your paper is highly absorbent, prepare it with gesso (gypsum mixed with glue) or white glue before using the pastels, so that the colors won't soak into the paper.
If you need to erase certain parts of your drawing, scrape off the colors using a sharp blade. This may damage the basic drawing paper, so be extra careful when doing this. Instead of erasing colors, you may change them by introducing additional colors. For instance, if you want to change blue into green, add some yellow on the blue. Apply a few drops of turpentine and gently mix the colors to obtain a green wash. Allow the drawing to dry and apply green oil pastel.
Use a comb, a blade, a palette knife or a pencil to create various textures on your drawing. Experiment with each of these: scratch the surface, write words or carve lines and spirals. Combine oil pastels with other water-based media such as acrylic colors. Use these colors before you apply the oil pastels and leave some areas where the acrylic-colored background is visible. Alternatively, apply the acrylic colors on oil pastels. Draw a few lines with pastels and leave uncolored areas on your paper. The acrylic colors will not adhere to the pastels, but will cover the uncolored areas. This is known as the "hit& miss" effect.