Park your car correctly, indicating to the curb. Turn off the Doof. Get out of the car and greet the plod with something like, "how can I help you officer" and then get ready for the smart arse comment like " what do you think you were doing" or "going a bit fast their we'rent we son" (when I have jeans older than him LOL). Resist the temptation to go the witty comeback. These people are trained to make you feel inadaquate, read the signs...eye contact and body language are very important, dont vomit the first thing that comes into your head, thats part of their plan to make you feel like a knob, they do hundreds of stops a year-you might get 5 of those. Slow down the repsonses, keep them short and offer no information that is not requested.
This is business, he/she is trying to take money from you...so never say thankyou.