The most difficult, and crucial, stage in treating your fish is the diagnosis of the disease.

Once you figure out what it is that ails your fish, the treatment is typically straightforward, and you simply need to follow the directions, so to speak and your fish should pull through.

I will be adding a disease diagnosis chart here in the near future.  Here is a good article about microscopes, and choosing an appropriate one for diagnosing fish diseases:

http://www.ntlabs.co.uk/microscope_diagnosis.htm

Right now, I'm looking at getting a new one, and as soon as I do will post a review on it, along with any pictures, if I can manage to figure out how to hook up my digital camera to it.