There are legal issues with them. In some states, they're allowed. In some other, they aren't. Sometimes it is even illegal to keep it in your car trunk. If they see it, they'll seize it, and fine you a lot. Make sure you look at the laws before driving around with it... including interstate travels (and don't even think about driving around with it in Canada).
http://en.wikipedia.org/wiki/Radar_detector#Legality
I cannot give you any advices because I only lived in places where it is completely forbidden (Quebec).
Most usual advice that just slow down around exit ramps and emergency paths connecting between the highways (especially if hidden by a patch of forest)... you will always see them with a sign. Cops love to hide at the emergency paths. When I lived in Pennsylvania, it gets easier because it's completely illegal for any cops other than the state police to use radar guns and the state police could only use that on interstates and state highways only.
I usually get caught when I'm close to 75, but the police always let me go. The grace is 5-10 mph in my experience, but don't push your luck beyond 10 mph.
Honestly, I do not see a point of speeding up to 90-100 mph just to save you a few minutes to get from point A to point B if just 10 miles away. It would make sense for me to go at 120 km/h instead of posted 100 km/h on a 800 km trip because it would take me only 6.6 hours at 120 instead of 8 hours at 100. It's a bitch to drive on Canadian highways at 100 km/h as (almost) nationwide speed limit. Not much civilization between highways... or even almost none for a half of day.
My personal record is 107 mph. Nearly blew the engine out out of my 1991 Buick Regal, but the car computer cut off the gas then. I can't wait to drive in Germany someday.