Reasonable suspicion is what they need to detain you. Probable cause is what they need to search. Slightly different burdens and a slightly different analysis.
If you’re contacted by the police, your first question should be, “Am I free to go?” If the answer is yes, then you are free to walk away. If they say no, then you’re detained. The Miranda rules don’t necessarily apply during a detention and there are different rules about searches during a detention, but the bottom line is that you still have your Fourth, Fifth and Sixth Amendment rights to be free from unreasonable searches, against self-incrimination and to an attorney, respectively.
If you are not free to go, you can politely, but firmly decline any request to search or provide a statement. The only thing you must do is provide your TRUE information. You cannot lie or do anything else that may be considered as delaying or obstructing their investigation.
Police: Hi, can I talk to you?
You: Am I free to go?
Police: Sure, but I’d like to talk to you for a minute.
You: No thanks. Have a nice day. (Walk away)
Police: I need to talk to you.
You: Am I free to go?
Police: No – you’re not under arrest, but you’re just detained while I sort things out. Where are you coming from (or what are you doing or other type questions)?
You: I respectfully decline to answer any questions until I speak to my lawyer.
Police: You’re not under arrest – I’m just trying to get to the bottom of things.
You: I understand. I’m still declining to answer any questions until I speak to my lawyer.
[Repeat as necessary]
Same thing with search requests. Under certain circumstances, they may legally be able to pat you down for weapons during a detention, but other than that, you have the right to decline a request to search. Do it politely, but firmly. The typical response is for the officer to say something like, “If you don’t have anything on you, there shouldn’t be any problem, right?” Same response from you. A polite, but firm denial of their request to search.
If they order you to do things, do not resist. That’s when attorneys and motions in court come into play, but the side of the road is NOT the place to argue with an officer about your Fourth Amendment rights.