Be Kind to the officer.
Police officers are just doing their job. They are well trained law enforcement personnel who normally avoid rude behavior and snide comments. However, they have a lot of control over the situation. If you are argumentative or uncooperative, the report will so indicate. Such behavior can be indicative of a person who is intoxicated. Moreover, it is likely that you are being taped on the patrol car camera. These videos will likely be presented to the jury/judge as part of the prosecution's case in chief. You do not want the judge, jury or the DMV hearing officer seeing less then cordial behavior on your part.
Follow Directions as best as possible.
The DA's case in chief will be based on all of the things you did wrong: you were swerving, you didn't pull over right away, you could not walk the line, etc. A good defense attorney will re-frame the case by adding all the things you did right. For example, that you were attentive enough to "signal" and pull over right away as soon as the officer began the traffic stop, you proceeded to the shoulder in a safe manner, you immediately provided the officer with information, you were balanced and coordinated when asked to step our of the vehicle. All of these things help prove you were attentive and not under the influence.
Be aware of the things that may hurt your case.
Know that the officer is trained to obtain evidence he can use against you in court. It is their job to enforce the laws of the state of California and watch for violations of the law. Often that is an active, not passive process. Be aware, if a police officer or CHP stopped you they have suspected something illegal has occurred. It is their job to gather evidence and that is exactly what they will be doing during. You are not required to provide evidence against yourself, which can be a sticky situation when trying to "be polite." Most importantly DO NOT admit anything. You are not required to tell the officer anything including how much you have had to drink. It is the state's burden to prove that you were driving and that you were intoxicated. Any admissions are strongly held against you. Don't do it. Also note that California Courts have held a DUI traffic stop is an "investigatory detention" and that Miranda does 't apply to questions asked while the officer is investigating.
FST and Breath/Blood Tests
Do however comply with the FST and alcohol screening. If you refuse it may be grounds for a one years suspension of your drivers license with the DMV. In California you are entitled to an election of a blood or breath test. There are varying schools of thought on which one is better. It is my experience however that breath tests are easier to exclude in court and that blood tests result in higher BAC's. Note that in practice Calfornia Law Enforcement Agencies no longer provides an option for a urine test.
During the detention/arrest
If you have not done so already, once you are handcuffed, immediately assert your right to an attorney and refuse to speak any further until one is provided. You may also request the officer allow your car to be parked instead of being towed. Sometimes they will agree if the parking is legal. After you are placed in the car you will likely be taken to either a "sub station" or "police station" for additional breath tests or blood tests. You still have to comply or risk an automatic one years suspension of your license with the DMV. You will then likely be detained overnight. While detained you will be given a phone call. Contact your attorney if you have one. Otherwise, contact a friend or family member. They may contact an attorney on your behalf or come to the jail to place bond or have you released under their custody.
After you are released.
Contact an attorney once you are released right away if you have not already done so. The first 10 days after the arrest are critical to keeping your license. If a DMV hearing is not requested within those 10 days then a person's license is automatically suspended. Also immediately write down everything that happened from the moment you got in the car to the time you were released. The police immediately write a report that they can use to refresh their memory. You can too. Plus, we are human and our memories fade with time. It will also help your attorney defend you.