One of the main problems I have come across is that normal house lighting produces a yellow or reddish looking coin pic.
I have purchased a 100 watt "Daylight bulb" (DONT get the lower 40 or 60 watt bulbs)which are found at any good lighting or hobby shop. They give a blueish light which makes the pictures more realistic when produced. They are also better used when cleaning coins as well.
I also use photoshop to make the pictures more "realistic" in colour, not to enhance the pictures but to get the colours more like the natural effect.
I also photograph through a magnifying glass on a stand with my camera on a small desk tripod. This makes the pictures much larger and gives more detail when downloaded onto the PC.