Draw, large, clear diagrams illustrating the experiment. Explain the diagram with text as needed.
A diagram, can be used to describe the set-up of an experiment, or it can define some of the variables used in the rest of the lab. (e.g. height of an apparatus, angle of incline plane, etc...)
This does not have to be an independent section, and can be included in the introduction.
A diagram taken from an external source must have a caption giving its source.