I suggest you try to find rules on how Audi car clubs judge cars. As an example, if you go to the Mercedes Benz car club web site, you will find the scoring sheet and rules for concours events.
If you can find the same thing for Audi, you will be in good shape knowing what to do. Call the organizers of the event (Audi club) and ask for the judging rules.
Once you find the rules, you will know what is important. I expect the underside and tires of the car will not be judged. But the exterior, interior, and engine compartment will. Rules will tell you much, for example in Mercedes, paint condition and finish may be less then 10% of the total score. In Mercedes, authenticity is important, what about Audi? Find the Audi guide lines.
When you arrive at the concours, plan to park the car and give it a "once going over." Make sure you are there early enough so that you have time to prep before judging starts.
You should be near your car when they are judging, in case something needs to be opened.
Lou