When approaching an intersection, you must come to a complete stop. You must also yield to all traffic, including pedestrians, and you must proceed when it is safe to do so.
Treat a flashing yellow light the same as you would a stop sign, but you must approach it at a slower speed and check for cross traffic. Yield to any vehicles that have arrived at the intersection before you and, just like you do at a stop sign, be aware of other drivers who may not follow the rules or may not be paying attention.
If you are turning left on a green light, you must yield the right-of-way to all traffic in the intersection before you turn. Likewise, you must yield to all cars that are traveling in the opposite direction before you turn right.
In many areas, drivers can get confused when a traffic light changes from yellow to red. This confusion can lead to accidents.
There are some exceptions to these exceptions, but it is still important to treat a flashing yellow light as a warning that the green light will end soon. As with a stop sign, you must come to a complete stop, yield to all traffic and then proceed when it is safe.
The key is to take a deep breath and remember that it's just a warning, not an indication of the light going red. Typically, you won't have to worry about getting a ticket for running the light.