In most professional forms of drag racing, the first one across the finish line wins. However, in bracket racing, that isn't always how it works out.
Most categories contains a wide range of E.T.'s, you are handicapped based on a time that you .predict. you will run. This is called your "dial in". The person who runs closest to their dial-in without going faster wins the race. If you go faster than your dial-in, you "break out" and automatically lose the race.
For example, if your Nissan Pulsar runs a consistent 15.10 and the Commodore you are racing dials in at 12.70, you would get a 2.40 second head start. If you both got to the finish line at exactly your dial-in, the race is a tie. In practice, this never happens due to differences in reaction times and vehicle performance.
The staging lights also measure how long it takes you to leave your staged position. This is called your reaction time. In .heads up. racing, it isn't a big deal, but in bracket racing it is very important. You must be consistent in your launch (via reaction time) and your car must be consistent in the quarter mile (via dial-in). Your reaction time is usually expressed as a number indicating how long you leave after the last amber light comes on. A perfect time would be .400, which is exactly when the green light comes on. If you get under .400, you "red light" and lose the race. If you take longer than .400, you will take longer to get to the finish line, which can cost you the race.
There are also different ways to "stage" in bracket racing. All strips use the standard "Stage" and "PreStage" lights on top of the "christmas tree" lights. These lights are tied to two light beams that go across the track, one immediately after the other. When your wheel breaks the first beam, you are "pre-staged". This lets you know that you are getting close to the starting line. As soon as you inch forward to the second beam, you light the "stage" lights. As soon as both lights are lit on both sides of the track, the starter will begin the race.
The key to winning the race is a low reaction time and a consistent performance by your car. If you run faster than your dial-in, you automatically lose, so if you feel you are running too fast, you might want to slow down just as you are approaching the finish line so that you don't go over your dial-in.
Eliminate variables between runs. Keep your car in the same configuration, do you burnout and stage the same way, shift at the same points, and do everything else as consistently as possible to win a bracket race. Compensate for changing track conditions using your dial-in (you can change it after each race). Also remember that slower cars are often more consistent, so you don't need to try to wring every last HP out of your car to win a bracket race. Have fun and remember, the first over the line doesn't always win in .dial in. racing!