Some excellent suggestions have already been made, if I could add and second them from my 6 years of shooting Art Repro this is what I suggest:
1. Software: Use CP1 Pro - If you are very serious about color acuracey the best combo I have gotten so far is the Colorchecker SG chart and Monaco Profiler 4.8 for your input profiles. The Monaco part may not be easy to obtain these days, so your next best bet is Pictocolors "Incamera" profiler. Again use the SG chart - but note it is semi-gloss which means you will be likely shooting polarized or controling your glare through other means. Making a LCC is also very important since you will be correcting not only for sensor dust, but also uneven lighting from your lights and light fall off from your lens.
2. Lighting (polarized) - For small work or very quick setup you can build two flourescent softbanks from PHILIPS TL 950 bulbs, you will need to have some wiring skills but its not hard. These bulbs have a CRI of 98, profile well, and I use them almost 99% of the time for in-house shooting (with large laminated polarizers, and mounts, you are looking at about $1000 in costs for two). For location and large work I like to gang up multiple hard lights. Strobe has its benefits for location since you can't always block out all other light sources, but there are some things that are an issue, such as flash to flash power and color consistancy. This might not be as big an issue if you are not profiling, but if the deviation is enough it will throw your whole profile off. That is one reason Bron was used in the past, if not for profiling issues then for the older MFB that were multi-shot. You need that consistancey there too - however! - there are other much less expensive options in strobe. Thankfully the Einstien 640w units give you this same consistancy. I use 6 of these units, 3 per pole with their standard gel reflector. The last option is 6 Tota lights running 300w bulbs (so your wattage doesn't get so high that you throw breakers, and if you use the standard 700w bulbs you run the risk of melting polarizers). Run these 3 per pole just like the Strobes, but you will need to use the Tota gel holders for your polarizers. This last setup is more expensive then the DIY flourescents but will light larger work and actually gives the most linear light fall off pattern - but because the WB is in the 2800k range when you correct for that it can increase noise (I believe in the blue channel) - they also take longer to setup for a shoot - like the strobe option.
3. Difficult Subjects - As it has already been said, polarization will kill metalics and other paints/surfaces that should remain reflective. But an easy enough work around is to photograph the artwork twice, once polarized and once without (or a variation thereof), then mask in those areas that need to stay reflective. I do this often with gold leaf and metalic paints.
4. Large work - At a certain point you will find it either very difficult to adequately light really long/tall pieces of work, in which case you should consider stitching by moving the artwork. There are many ways of doing this, some not so elegant, other with moving walls, etc. But the basic idea is to perfectly light a smaller area and move the artwork through it, recording it in sections. This also yeilds more resolution - though if your technique is bad you will lose some of that when combining your files.
5. Lastly, Alignment: Various products exist to help you get perfectly square with your artwork. One is the "Zig-Align." Their website is a little difficult to understand but they can make recommendations over the phone easily. The downside is that each time you move your camera you have to re-align, which takes about 5min. For varied sizes of work this will drive you mad, unless you build a dolly setup where you can move the camera forward and backward and it remains stable and squared.
Hope this helps!
-John
