Get a business sized card, which says "My name is ______. I demand a lawyer to be present during all questioning. I do not consent to any searches." Hand it to any cop who detains you. Have spares; you'll probably need them.
Thanks to various SCOTUS rulings, if you have not requested a lawyer, your right to remain silent must be expressly invoked at every refusal to answer a question, and if you don't invoke your right to remain silent, they can introduce your silence against you in court. Once you have requested a lawyer, questioning must cease and not resume until the lawyer arrives. If you want to answer any of their questions, have your lawyer relay your answers; answers relayed in this manner cannot be introduced as evidence against you in court.
If, after handing the police this card, the police search anyway, then have the lawyer submit another card like this one at the motion to suppress. Having the statements in written form eliminates any ambiguity about the intent of your statement. The police can easily twist an oral refusal:
The policeman asks, "Do you mind if I search your car?" You say "Yes," meaning that you do mind and are not giving consent. On the witness stand, the policeman will testify that he asked if he could search your car and that you said yes.
The policeman asks, "May I search your car?" You say "No," meaning no. On the witness stand the policeman will testify that he asked if you minded if he searched the car, and you said that you didn't mind.