I do this fairly often. My usual set up is to set up the camera on a copy stand and use two studio strobes with plain reflectors at about a 45-degree angle to the work. It's good to check to make sure the camera, stand, and artwork are all level, or if you have a laser alignment tool, even better.

Using an incident meter with a flat diffuser, I check to make sure the light is even at each corner and in the center, and adjust the lights accordingly, but as long as I've measured the distance between the strobe heads and the work from the lens axis accurately, little adjustment is necessary, if any. If you don't have an appropriate meter, put a sheet of white paper where the work will be and hold a pencil under the lens axis perpendicular to the paper, and check to see that the shadows are even on both sides.

Some people cross polarize by using polarizing gels on the lights and a polarizer on the lens. In my opinion, this is necessary only if the surface of the work is uneven or textured, as an oil painting. Set the lights properly, keep the work flat, and there will be no reflections to cancel out.

Sometimes I've done this work at our university's fine arts library, where they have copy stands set up with 5000K fluorescent tubes. These are very simple to work with, if you have access to them.

You want to use a fairly neutral film. Kodak EPN (Ektachrome 100) is ideal, but other possibilities would be Astia 100F (a little muted and cool), Provia (a little more punchy), but avoid super saturated films like Velvia, Ektachrome 100SW, and such. Of course if you have a tungsten light source and don't have filtration, use a tungsten balanced film.

If you want to do this outdoors, do it on an overcast day or in open shade. For neutral results with daylight film under such conditions, you'll probably want an 81A or KR 1.5 warming filter.

Try to avoid using the zoom lens. Tele-wide zooms all tend to have barrel distortion at the wide end and pincushion distortion at the long end. Even with a high-end lens, it can be subtle enough to be maddening, if you're obsessed with such things.