do a search on the 'l/s strategy' or something of that kind. basically its a well documented strategy that performs quite well. it's assumption is that the public opens the day and the professionals close it...if the price at 1pm or later is above yesterday's high, then go long. if price is lower than yesterday's low, then short.
they did an analysis of what the BEST time to enter trades, all the way to 10am. it turns out that 1pm is the best, 10am being the worst performer.