Microscopy Podcast
Heat-fixing and staining human cheek cells
Observing human cells is a good introductory activity to learn heat-fixing and staining.
Staining bacteria
Here is yet another link to an article from Popular Science magazine.
Stains and reagents for microscopy
I found an article in Popular Science Magazine (see link below) which gives a general overview of different stains that can be used in microscopy.
Staining of Onion Cell Nuclei
This is a simple preparatory technique that allows students to observe the otherwise difficult to see nucleus of onion cells. There is no need to employ, possibly harmful, DNA staining chemicals.