Lighting off the camera is going to be a distinct help, but you probably should be aware of a few things in doing so:

1. Hotshoe flashes are small lights, so you want some diffusion if possible. This can be an umbrella or even your own homemade reflector that you point the flash at. Anything that softens and spreads the light so that the source is not concentrated.

2. You'll probably have mixed light, especially if the flash is more for fill (and that probably makes sense). This means that you might need to put a gel on the front of the flash in order to get proper white balance. So, for tungsten lighting, you might need a CTO (color temperature orange) gel and for flourescent, a plus green. I do note that is a case of you might need it, it depends on the ambient lighting. Either way, you can usually get these gels at decent camera stores.

3. Angle of incidence equals angle of reflection. You have shiny surfaces and you need to angle your light to avoid having it reflect directly back into your lens and blowing out the scene. Ever notice when you see eye glasses wiped out by flash? The way to avoid that is to raise (or lower) the flash so that the light is angled so that when it reflects, it reflects down and out rather than straight in to the lens. This well nigh impossible to pull off if the flash is mounted on your camera and pointed at the subject.

4. Kind of in line with item 2, get a gray card (or some other aid) to get correct white balance and shoot this card at every location. If you shoot raw, rather than JPEG, then you can use this get correct color and then mass apply that to all images at that location. Very handy and saves enourmous amounts of time.

That covers my thoughts... If I have more, I'll add them.