Agreed with pretty much everyone here. I'm not at all anti-police by any means, but there are too many bad cops out there to just automatically trust them all.
All that I can add to the conversation is don't let the cops search your vehicle, person, house, etc. without a warrant. If they ask, tell them no, and if they proceed anyway, make it clear that you object, and the only reason worth stating is that you have a constitutional right to be free from unreasonable searches and seizures (because they will ask and poke and prod if you don't consent to a search). You stand to gain nothing by cooperating. Conversely, the only reason they are asking is because they think they can build some kind of a case against you, but they don't have enough information to get a warrant. If you let them go ahead, there could be a crooked one in the bunch who lies in a report, falsifies evidence, plants evidence, etc. Basically, you stand to gain nothing, but stand to lose a lot.