I exaggerate my colors in Photoshop simply by pumping up the Contrast and Brightness or plotting severe dips in Curves.
Polarizing an image in Photoshop can enhance the features of the scans, picking up on small flaws and light lines. Test each level because each will react differently
I also play with the Shadow/Highlight feature under Adjustments to alter light sources further.
Mostly I let the scans speak for themselves.
Don’t be afraid to change the position of the scanner, tip it on its side or have someone hold it (Note of C. Staebler : read the scanner User Manual before doing this, some scanner don't like such manipulations).
Play with darkening the background by covering an individual with a heavy fabric or remove scanner lid for dual light source.
Bring props! Anything can be scanned (obviously think about it). Transparent gels can be used to give a burst of color or a more “Photoshop” ed feel.