Hi Ken.
I am doing a lot of Genealogy as well. Research and copying photos.
Very simply. position the book or document any where so there is no lighting behind you which will reflect on the image. For example on a table where there might be a gap between lights on the ceiling behind you. Use a LED or similar lamp at about 45 degrees to one or 2 sides to illuminate the image on the page.
Position the camera square to the image so it fills the view in the viewfinder in camera. Any image that might not be exactly square I fix or crop in photoshop to tidy the image so it reproduces well in your document.
If the light is persistant behind you just get a piece of cardboard or similar to block out the problem.
Hope that helps..
peter