Notice how some speed limit signs say "maximum", while others don't? That's primarily because those that don't say "maximum" are posted for safer driving conditions, such as in rain, heavy pedestrian traffic areas, dark streets at night, etc. If you can prove you were not a hazard, you can get off. For example, you could argue it was a sunny dry day, there were no pedestrians, and you were driving with the flow of traffic. Most speed limits are more like guidelines than hard-and-fast rules (except in parking lots, private residential areas, etc).
That's another thing: everyone is taught during driver's ed that you are supposed to drive with the flow of traffic. Going either too fast or too slow compared to other vehicles can be hazardous. For example, if you're doing 40 in a 45, and others are doing 50, the cop can pull YOU over instead of the speeders, and you will pay a fine in court...you can't win a case like this. But if going with the flow of traffic, and not presenting a hazard to others, a judge will often dismiss the ticket entirely.
Another trick: look for a section on the ticket that states whether or not the officer has requested certain days not be scheduled for a court date due to vacation, days off or whatever. Most likely, your court date will be scheduled a week or two before that. Then just before the date, request an extension. If you're lucky, you'll get a date when the cop is on vacation or on a day off. He's not gonna show up.
You can also request documentation. For example, get the papers that show the last time the radar gun was calibrated. If it's been more than a few months, or the gun was repaired more than a couple of times or has been proven to be incorrect in other cases, or even if the document wasn't signed by a superior, these are considered mitigating circumstances and/or technicalities. They have to provide you with these documents upon request...it's law.
The document should also show the distance the gun was from you when you were clocked. The further away, the less reliable the reading. Especially if there were other vehicles: in this case, you could argue he clocked somebody else, and you got tagged by mistake.