Draw a large circle for the shell, and add a smaller circle for the head to its left. Make a curved line beginning at the center of the head and extending below and passed the large circle.
Sketch a large crescent-shape within the small circle for the snail's mouth. You may add two curved lines for its teeth and tongue. Next, draw the eyes by extending a pair of tube-like shapes above the top of the circle. Add a small circle on top of each, and form the rest of the snail's facial structure by adding a chin. You may keep the face within the circular guideline or shape it however you choose.
Draw a bean-like shape for the body. Make sure it is narrower toward the shell end. Next, sketch a swirl pattern within the large circle and connect it to the top end of the body. Complete the shell by tracing out the guideline. Finally, draw a tail extending out the other side of the shell.