What are the four rules of natural selection?

Natural selection has no 'steps'. It is a continous process of filtering. However, there are a couple of key factors in natural selection, prerequisites that have to be met for natural selection to occur:

Overproduction-many organisms are produced

Genetic Variation-some organisms have different genetic traits than others

Struggle to Survive or Survival of the Fittest-The organisms with the traits better suited for their environment live while others die off

Successful Reproduction-The living organisms produce giving their offspring better traits to survive.

This process goes on changing a whole species. It is a big part of evolution. This helps organisms become the best suited to their environment that they can.