If you are into gambling, I'll give you a more hands off tip.
Instead of keenly watching the price ticker (which is delayed anyway unless you fork over tens of thousands for a BBG terminal + real time price), try to set high/low price. e.g. Let's take MSFT for an example. Open price (fictitious) was 205. You anticipate it will go down to 200 before bouncing off. Place a limit order for 200.
Next, when you want to sell, place a similar limit order for whatever your target price is. Let's assume you anticipate there will be a closing rally which will drive the price at least to 210. So place an order with that limit.
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Besides such day trading, you should ALWAYS use limit orders. There are many weird market situations where the computers may drive prices too far one way or the other and you will be left holding the bag with a market order.