Use a diamond, triangle, and rectangle for windows. Put a long U-shape under the windshield and a curve around it. Form oval headlights and a banana-shaped bumper. For the front axle's differential housing, draw a U-shape with a curve and rectangle on opposite ends.
Use curves for the rear housing. Place a banana-shaped figure above it. Sketch a U-shaped front wheel well; make a question mark for the rear one. Attach a curved rear bumper.
Now it looks more like a truck, but what about the "monster" part? On the next page, we'll add eyes and fangs to our cartoon.