It is my observation, there are 3 periods that is best to trade in a day. One could plot his move based on the anticipated move of the market.
8:30-9:00, This is emotion trading. A lot of swings. if you have a good trade overnight, it will brighten your day. if you have a wrong trade, this is also the good time to close your position. Just do not panic, wait for the first wave of Selling/buying subbued and then make your move.
11:00-1:00. This is when momentum players coming. if you have a stock going high, very likely it will get even higher. so, if you are a day trader, this is the time to close and your are done for the day.
2:30-3:00. This is when index funds/ETFs to coming to adjust their position to reflect the market and also a good indication for tomorrow. In a normal market condition, you can short/long a momentum stock and be ready to take advantage of the emotion next day.
CHL of the day.... buy before 11:00 (central time).. buy before 2:00 central time