These are the times when many traders simply pack up and take a vacation for the last couple weeks of the year. Volume is light and the markets either do very little or they have erratic trading and many false signals.
This year has a compounded problem with the fiscal cliff issue that is holding the markets captive. There is no telling what is going to happen by January 1, but the markets don't have a good feel going into the weekend. The Dow was down 158 points on the day. Most commodities were also lower on the day, while natural gas actually had a positive day on cold weather support in the north.
I prefer not to do much trading during the end of December. It really isn't worth the effort most years. The trading opportunities are hard to find and the last couple of weeks in December don't really add much to overall gains for the year - if any. Longer term positions in diversified trading systems tend to do fine during this period as the markets don't tend to move much.
In the overall scheme of trading, there really is no better time to take a vacation and spend time with the family. Come into the new year refreshed and ready to trade with a clear mind.