This photo was taken about 10 years ago using a conventional SLR and color print film.
Light is natural and coming in from a window at left, background is a piece of green poster board, camera is about 3-4 inches above the glass.
The main difficulty in using natural light is that everything around the glass is illuminated to the same degree as the glass itself. This creates strong reflections in the glass, so most of our energy and wit is going to be devoted to trying to minimize them.
Reflections:
In the first example, we can clearly see reflections in
the glass but they're
subtle and don't distract. To keep them manageable, I
chose to photograph on a cloudy but bright day and I set the
glass up in a window in a south-facing room. Bright and
cloudy gives a diffuse wash of natural light. The absence
of direct sun means that there are no dazzling hot-spots either
in the room or outside to reflect back in the glass.
Background:
Backgrounds should be chosen to be as neutral
as possible. The easiest way to do this is using a largish
piece of construction paper or poster board (somewhere around
18" x 24" or 24" x 36" works well) in your favorite color.
Choose a shade that will provide good contrast for the
shot-glass label, such a mossy green or a navy blue. Tape one of end to the table and the other to a convenient
vertical support, such as a stack of books, creating a seamless
curved "L". Place the glass at the front
of this L close to the piece of tape and then place the camera
lens directly in front of the glass and and an inch or two above
it.
Contrast: Look at the glass through the camera lens
and see how well the label stands out against the
background. If the background is too light, the label will be indistinct.
One way to darken the background is to put
it into shadow using a book or box, for example, or a convenient shade
if you're photographing in a window.