The first rule is: there are no rules.
The second rule is: pick the color you love.
The third rule is: repeat rule #2 in a different hue.
Gone are the days of matching your handbag to your belt + shoes. One of my fashion foundations is adding an accessory in a color that is not in my clothing. It works beautifully on you, so why not on your table?
These are napkins we are talking about. It is a small color commitment. Seriously. The beauty of the napkin is that it is no commitment at all. Because, at the end of the meal, the napkin can go away, unless you are like me who likes to fold neatly and leave on the table for a little color enjoyment any time of the day. But, I digress. My point is that there is plenty of “distance” on a table and matchy-patching the napkin to the drapes, upholstery or china is not necessary. Pick up an accent color if you want or don’t match anything at all. Just set the color that follows your rules.