I missed the question about settings. Here's what I do...
I always shoot in jpg, never raw. Never found much advantage to raw, and it's a lot more work that I don't need.
But, you need good camera settings to get the most from the camera's jpg engine.
FIrst, you need to ensure you don't over-expose. I shoot in Aperture Priority Mode, and then set exposure compensation typically -2/3EV to make sure the camera minimizes over-exposure.
Second, to minimize lost shadows, you need to make sure the shadows map into the jpg by making contrast as low as possible, and take advantage of your camera's dynamic range optimizer if it has one.
Third, shoot at reduced saturation. This improves dynamic range, especially for coins with lots of color. It's easy to increase the saturation in post processing if needed to match the color of the coin.
Always use manual focus, and ensure you're critically-focusing on a middle-height feature.
Those are the most valuable tricks, though of course the most important is getting the lighting right.