This one is EASY. In all the years that I have been practicing, I have not once seen a situation in which it was to your advantage to talk to police without counsel present. There's a reason you have a right to remain silent. Police will often try and get you to talk to them by assuring you that "things will go better for you", or they'll "put in a good word for you". Think for a moment about the value of these "promises" and what exactly you're getting in exchange for giving up your Constitutional rights. Nothing. Police either have evidence against you or they do not. In most cases if they have evidence they're going to go after you, whether you cooperate or not. They're not going to "give you a break" simply because you admit what you did. The reality is that if police want to talk to you, it's often because they don't have enough evidence to have you charged, and so they want YOU to make it easier for them to avoid having to go out and actually investigate.
Don't convict yourself by thinking that you're a smart negotiator who can outsmart these professional interrogators. Stay away from police. As soon as they start asking you questions, tell them "I want my lawyer present". Do not ask them if you should have a lawyer, don't ask to talk to your parents or spouse, don't ask if it's "necessary" to have a lawyer; just state clearly "I want my lawyer present".
If you say anything at all to police, they will then be able to distort what you say and put damaging admissions into their reports. I can't tell you how many times my clients have looked at police reports and said to me "I never said that"! Don't give them the opportunity to do this to you. You have a right to remain silent. Use it.
If you've already made statements to police, don't feel bad, you've done what most people do. I've represented cops and lawyers who should all know better and even they talk to police, getting themselves into trouble in the process. There are sometimes things we can do to keep these statements out, but in general it's best to avoid the problem in the first place by not speaking. If you've already spoken, stop and don't give any more statements.