Here are the geometrical rules for drawing ray diagrams:

1. *Incident ray*: Draw a straight line from the object to the mirror/lens.
2. *Normal*: Draw a perpendicular line to the mirror/lens at the point of incidence.
3. *Reflected ray*: Draw a straight line from the mirror/lens to the image, making the same angle with the normal as the incident ray.
4. *Refraction*: Draw a straight line from the object to the lens, and another from the lens to the image, bending at the lens surface.
5. *Virtual image*: Draw a dashed line from the mirror/lens to the virtual image, behind the mirror/lens.
6. *Real image*: Draw a solid line from the mirror/lens to the real image, in front of the mirror/lens.
7. *Object distance*: Measure from the mirror/lens to the object.
8. *Image distance*: Measure from the mirror/lens to the image.

Remember to use a ruler and protractor to ensure accuracy!

Let me know if you have any specific questions or need help with a ray diagram!