Advice from (much) older brother:
"Don't argue with a cop, that's not their job. Argue with a judge.
Don't tell a cop stupid lies. He's heard them before, and it will just piss him off.
Always say "Yes sir" and "No sir" to a cop. They like it when people do that.
If a cop tells you "You're under arrest" say "Yes sir" and do what he says."
Over the last 25 years this advice has saved me from 5 traffic tickets, 3 arrests, and most importantly:
When I was younger (20-ish) I was arrested twice for "Public Intoxication". However, since I was so agreeable, they cops didn't feel the need to do a body search, and I spent the night in jail with a bag of pot in my sock and was released the next night without being busted for possesion.
One of these times, one of my friends wanted to argue with the cop about "harassment", I kept telling him to shut up and walk away. The cop told him to listen to me, but he kept going on and on (he was drunk too).
I got popped for intoxication, spent the night in jail and walked out without a fine. Walked out with my pot, BTW.
He got arrested for "Interfering with a police officer", his family had to put up a $50,000 bond to get him out, and he got a $5,000 fine and a year of probation.