Hi Rich- Glad you liked it!!
I would be greatly interested if you put more of your work up....
the answer to your question has a few answers...
In the PSP program, it is easier to crop out the figure( or tube it as we call it..lol) with a white or light background.
as for the glass, the black works better as the glass would have gotten "lost" in a white background....I had to keep the dark background
Really , whatever you do I can work with it, or make it work..