It used to be that you could make a decent living using news to intraday trade, providing you were astute and faster than others at getting your order in. These days the power of computers has really negated that. All types of funds have computers with rudimentary artificial intelligence watching the news on key names. If a headline or article comes out that is bullish, they flood orders in within one second automatically. This basically makes it very difficult to profit for an individual trader UNLESS the news is major and it should affect the price over hours and days of time. In this case you can still jump on board.

Figuring out which news will have a major impact is not that hard, but its still tough. Basically anything that is unknown and would majorly affect earnings is valid for this. For example, getting a super large contract that is unexpected (this is key, unexpected means you know the company ahead of time and know this was not in the pipeline or they were expecting 20 million only and got 90 million etc), a key drug approval or discovery (not pre clinical, these usually dont do much). Earnings that are way way above estimates (or way way below) can also cause a new trend to form in an otherwise dull stock, again assuming that the market did not anticipate this event.

One thing to keep in mind if you play any stock based on news. If the news is good, and the stock SHOULD be moving up and instead its doing the opposite for a decent amount of time, caution is advised. You are not the only one to figure it SHOULD go up, but funds with larger shares think the other way. These guys are the ones who move the stock. If they think its an opportunity to sell, dont stick around and wait. If the reason for the entry was the news, but the price is not working, exit the trade and move on. Other people are trapped as well, and this tends to accellerate the trend in the perceived wrong direction. Often times its a subtle detail that the funds figure out that the average trader and even professional trader will miss, and this is why they are fading the news - or sometimes it does not matter, they just want to get out of a position regardless of the news, and the increased volume because of the news event helps them out.

Trading in the stock market is all about stock selection AND timing. You can have the greatest idea and be right on direction overall, but if you pick the wrong timing to go in, you will lose by getting stopped out only to watch the stock move in the desired direction later in the day. This little fact here tends to lead newer traders down the false path to NOT use a stop. While this may work when the market is choppy and its easy to get stopped out, over longer periods of time this is a recipe for disaster. Not getting out after the stock has moved 1 point against you leads to holding something that is 15 points against you and at a huge loss.

Here are some basic rules to help people with stock timing, including those people who are longer term investors:

1. Identify key support and resistance points. These will be used for stop loss placement AND target prices once in a trade. Entering a stock that is too far away from support increases risk IF it turns back down.

   
   

2. Pay attention to many stocks and their behavior. Meaning do stocks approach resistance and mostly turn lower, or do they stall there then push higher and breakout? Do stocks sell down to support (usually near it, rarely right at it) and hold and bounce, or do they stall there then breakdown to new lows by a significant amount (2-5% lower). These 2 aspects alone can improve results. Why buy a stock near support IF most names are not holding and they break them lower? Most of this has to do with market sentiment.
3. Know all the major news due out each day. Know the major companies reporting earnings, both before the open and after the close. Especially pay attention to companies in the SAME INDUSTRY as a stock you are holding or plan to add. Overall, its usually a bad idea to add a position before any earnings event - that is gambling and creates large swings in volatility overnight - none of which you can control.
4. Know the major economic data due out for the day and the week. Also pay attention to which ones seem to be moving the market of late. This changes over time depending on the focus. Usually the market will primarily focus on only 1 or 2 items which will affect its movement - it will pretty much ignore the rest, even if the numbers are off from estimates. Wall Street can only focus or care about 1 or 2 major themes at a time, not 10. Realizing this will help you from overanalyzing and guessing about market reactions. Only concentrate on those numbers that the market cares about.

There is a lot more to timing than this, but these basic rules should help with timing, and a lot of them I see people violate every day. While they will not improve results from poor stock picks, they can help out those who are more diligent in finding day trading ideas.