The DUI Timeline

This is what can happen if you are pulled over. The timeline starts with:

Erratic driving or any reasonable belief by law enforcement that a driver is drunk. Please refer to the Reasons Police Will Pull You Over section.
Answering the question, ‘Have you been drinking?’ is not a requirement. You are not required to answer any self-incriminating questions. You can politely refuse and you can ask for an attorney. Remember, it’s not illegal to drink (if you are over 21) and drive as long as your BAC level is under .08.
Field Sobriety Test—this will determine your level of impairment, NOT your BAC levels. You are not required to take this test and there are no legal ramifications if you don’t. A polite refusal is OK.
Chemical Test—determines your BAC level. You will be asked to take either a Breathalyzer test or a blood test to determine you blood alcohol content. IF you refuse to submit to ANY testing, in the State of Illinois, you will face legal ramifications in court. Breath machines are more unreliable than a blood test (please refer to the Breathalyzer section for more information). If you really feel you are sober, ask for a blood test, as it is the most accurate.
You will be released if you pass your Field Sobriety Test and you Chemical Test shows that you are under the legal limit of .08 (or .04 for commercial drivers). If your legal limit is .08 or higher OR you are under 21 and you have ANY alcohol in your system you might be taken to the Drunk Tank, i.e. a holding cell. You will be kept in the Drunk Tank until you either SOBER UP or you can be kept until your first ARRAIGNMENT.
Hire an attorney. It is not advised to represent yourself in these types of cases. Find a good DUI attorney by reputation or word of mouth. Find an attorney who SPECIALIZES in DUI litigation. Also make sure that attorney has a good track record of actually going to trial. Be advised, attorneys are generally expensive no matter where you are.