Put yourself in the shoes of the casting director . They have to find a few select candidates out of hundreds and have at least one of them meet the expectations of the director.

In turn, the director is juggling hundreds of details to try and produce a marketable commodity that's going to make money for the investors.

Both of these people are trying to manage their time and dozens of different risks. That's one of the reasons that the same people, even people with minor roles, keep showing up again and again in film and television - they've proven that they're not going to waste time, and they're not going to be a risk to the production.

To get a casting directors attention, do the following:

1. Have a great headshot that looks like you. Your headshot is your business card. Spend the money for a good one.
2. Have a good reel that demonstrates who you are in less than a minute. Avoid the intense emotional scene or scream fest. Just show them what you look like, sound like, and how you move.
3. Keep your resume up to date - classes, stage work, commercials, independent film, etc.
4. Be available via the phone number, email and/or text account you've listed on your resume.
5. Show up on time. That means arriving early enough that you're settled and ready to audition. You're not thinking about where the car is parked, how you almost didn't get there, what you're going to do after the audition, etc. You've got to be present and be ready to perform.
6. Be prepared. If you got sides before the audition, know them. Know what your character wants, what obstacles are in his/her way, and know how you as an actor can demonstrate that.
7. Be professional and courteous, but not subservient. Think of yourself as part of a collaborative team, with as much value as anyone in the room. Show that you have energy, and that you're going to be a positive source on set. One note - don't shake anybody's hand unless they offer it to you first. These people are going to see scores of people in a day, so they may not want to take time away by shaking everyone's hand.
8. Be confident in your work and don't apologize. Would you want to go to a surgeon who seems uncertain? For that matter, would you even want to go to a mechanic who seems a bit scared to work on your car? Stand up there, do your stuff. In the martial arts, they say “belts aren't given, they are taken.” Nobody will offer you a part if you don't look like you can take it.
9. Be flexible and demonstrate that you can respond to direction. Do the initial reading to the best of your abilities as you understand it. Hopefully you'll be asked to do it again with some variation. Consequently, you should think about a number of different ways the part could be done, and they should all be emotionally valid.
10. When the audition is over, say thank you and leave. This is the last opportunity you get to prove that you're a positive person, and that you're not going to waste any time.