What should I do at a DUI stop in Georgia?

If the law officer instructs you to step out of the car, you must comply and do so.

If the law officer asks you to perform certain tasks for a field sobriety test, you can politely refuse to perform these tasks.  Ask your self  and make a mental note to yourself, if you have any balance or weakness problems?  Are you often dizzy?  Are you dizzy now?  Are you nervous about the situation you are in and about the task you are being asked to perform, so that it may degrade your ability to perform these tasks?

Refusal to take the field sobriety test is not illegal.  You may still be arrested.