Receive a moist paper towel and wipe from the surface in the pumpkin before you start drawing. This could clean up way any of those little Filth or dust particles continue to clinging to the surface. It is possible to try and tape a plastic stencil on to the pumpkin, https://how-to-draw-a-halloween-p53208.digitollblog.com/27836939/getting-my-how-to-draw-a-halloween-pumpkin-easy-to-work