Check out the resources of Nikon MicroscopyU, this is a very detailed web site exclusive to the subject of microscopy. Nikon even runs an annual competition.
In the area of using a dSLR on a microscope, check out About the Use of Digital Single Lens Reflex Cameras on Microscopes and Connecting a camera to a microscope.
Edmund Optics has technical resources for Microscopy along with optical components to adapt a camera to a microscope.
That will provide a lot of information, you'll see microscopy can be a speciality all unto itself, you may want to make microscopy a career, and no one will ever see you again, well, out side of your lab.
Nikon MicroscopyU SmallWorld 2014 Competition - 1st Prize - Mr. Rogelio Moreno
Panama, Panama
Specimen: Rotifer showing the mouth interior and heart shaped corona (40x)
Technique: Differential Interference Contrast