[This is by Arthur Taylor who deserves considerable credit for it. Accessible, readable, and completely correct. I couldn’t have said it better (nor probably as well). Read, peeps. No one ever plans to need this advice.]
The first thing you should do when questioned by the police is ask if you are free to leave and insist on an answer. If you are free to leave - do so immediately, even if the officers tell you that you’re acting against your best interest (that’s their opinion and it’s their interests they’re concerned about).
If you leave, questioning is over. Get up, walk out, don’t look back, don’t respond to anything you’re asked or anything that’s said to you.
If you are not free to leave, politely say that you want to speak with a lawyer and have the lawyer present during any questioning. (And no decent lawyer is going to allow questioning to occur.) The questioning should stop immediately - but there may be continued cautions that, in the opinion of the officers, you’re not acting in your best interests.
Do not pay any attention to those cautions, let your lawyer make that call. Keep repeating the above request for a lawyer like a mantra. Yes, it may mean that you have to wait for a lawyer, but if you are not free to leave, you have some serious concerns anyway - don’t make them worse.
Keep in mind that police officers are trained in interrogation techniques. They are very unlikely to flat out ask if you committed a crime. They are going to solicit little bits of information from you that don’t seem important - to you. But, when pieced together these pieces of information can become quite condemning. A very common technique is to make the subject of the interrogation believe that they are helping themselves and that once they get a lawyer they won’t be able to help anymore. “This is your chance to help. Once you get a lawyer, they’re not going to let you talk to us and clear this up.”
The police can also lie or misrepresent facts to get the suspect to respond during questioning. They can tell you that they have evidence they don’t. They can tell you that they have witnesses they don’t. They can tell you that an accomplice has confessed who hasn’t. All of this is designed to get you to respond. Don’t.
(1) Ask if you are free to leave - and, if you are, do so immediately; (2) If not free to leave, keep politely repeating in no uncertain terms (over and over, if necessary), “I want to speak to a lawyer before any questioning and to have my lawyer present during questioning.” Do not respond to anything else.
Your rights protect you from more than strict grammatical questions, they also protect you from statements that try to provoke a response. Everything an officer says may not have a question mark at the end, but it may very well be said in order to get you to respond.
If you want to speak to a lawyer and you can’t afford one, one will be appointed for you at no expense.