Hi Katlin - congrats on your audition! I've done a lot of commercial auditions and I've found these tips to be helpful:
If you haven't gotten any copy (dialogue) before the audition and you're not sure if you'll have lines to say, arrive 20 or 30 minutes early. More and more these days, they will only have the dialogue available at the audition.
When you get there (early), grab a copy of the dialogue, but don't sign in yet. Just find a quiet spot and work on it. Then a few minutes before your call time, go sign in.
Some sign-in sheets still ask for your social security number - do not write it in. If you book the job, they will get your SS# when you sign the contract. You don't need to write you SAG-AFTRA number in either - I always leave that blank. Fill out the rest, including your name, agent, etc. NOTE: If you run into overtime at an audition (over an hour) and you want to claim it, be sure and put your SAG-AFTRA number on the sheet and sign out.
Don't spend a lot of time talking to other actors. Getting caught in the middle of a conversation when your name is called means that you're not going to be prepared and in the right state of mind. Remember, auditions are business time, not social time.
And forget about talking on your cell phone. I was at an audition last week and the woman going in ahead of me was on her phone talking to someone when the casting director came out and called her name to come in and read. The actor had to say goodbye, end the call, and put her phone away in a special pocket in her purse. All the while keeping the CD waiting. This made the actor look unprepared and rude. Not a great way to start an audition!
Most casting offices won't ask for a headshot and résumé, but always have one you can give them if they do ask for one. Most of that stuff is sent electronically from your agent.
Also, be aware that the session director will often call in a group of actors to explain what they want the actors to do in the audition. Don't miss that! It's also a good time to ask questions if you have them.
For me, the main thing I work on before an audition is focusing and getting into the zone. The audition should be the most important thing going on in your life at that moment.
And don't forget - you can also do some preparing on the way to the audition by vocalizing and doing some visualization exercises. (Although maybe not visualizations if you're driving!)
Hope this helps - and break a leg!