If you are arrested for a DUI/DWI there are three things that you must do. These are things you should do in every case.
Do Not Fight With the PoliceYes the cops may seem rough and they may be indifferent. They do not have to do anything other than act professional. If you fight with them you risk having a refusal by conduct. Currently in Minnesota that results in a new crime of "Test Refusal" and it is more serious or can make your charges more serious. They may ask you to take a breath test called a PBT. This is not the "official" test. The "official" test is given at the police station. If you refuse the "official" test it is more serious as the law currently stands.
Call an Attorney, they don't mind be awkened to help you make a decision.You have the right to contact an attorney before testing. No matter what time of day, DO THAT. Call someone. If you do not succeed on your first try, keep trying. The cops will give you a phone and phone books. If they do not it could result in the test being thrown out of court. Do not assume that just because its late or you do not know any lawyers, that you can't call, you can. Many lawyers take calls at all hours. If you call and talk the advice can be worth alot to you, especially if you think you may test over .16. Be aware that the attorney should be told about all your prior offenses if you have them. You should tell the lawyer how much you drank and when. The lawyer may be able to do a rough calculation on what you may test and will help you decide what to do.
File a challenge to the license revocation, this is called an "Implied Consent Hearing".This is an important step. You only have 30 days to challenge the revocation of your license. Many clients come in and they have waited till their first court appearance to talk to an attorney. At that point it is usually past the 30 day deadline to file for a hearing on your license. Don't let that happen to you. Much like the section above you should contact a lawyer and at least discuss your case. Most lawyers that do DUI/DWI work will give you a free consult, use it.