Well depending on how much manual control you have of your camera you should be able to take very decent pictures. If you can manipulate the shutter speed you can adjust the exposure such that even a dimly lit room will yield all the light you need.  You should never use flash if at all possible. Experiment with longer and longer exposure times to figure how much you need before specimen gets over exposed (to much light). If you cannot adjust the exposure time you'll need to add more light via desk lamps, over head lighting, LED's, even using sunlight if possible. Some say that light is almost entirely what makes a good picture.  Get your light situation taken care of and I'd say you're more than halfway to a great picture.

Oh and I forgot to mention that if you lengthen your exposure time you'll definitely need to have a tripod.  You can't hold the camera and take good specimen photo's as they will be very blurry and poor quality.

Also, catch the light before sunrise, just after sunrise, before sunset, and just after sunset.  The light is more diffuse and approaches from a low angle, so you can play with that as you arrange your shot.  You have to move fast because the ideal light does not last long.  (The overcast and open shade techniques can  be used throughout the day at leisure.)