11. Embrace your faults. Monson explains that people shouldn't necessarily think their faults will be dealbreakers. "It could be the thing we love about you," she said.
12. Relax and don't let your nerves rattle you. What's the first thing that gets someone noticed? "Confidence," O'Neil said. "They are natural, they are at ease, like they are talking to a friend. They are not nervous."
13. Tons of reality-TV show experience might not be a good thing. O'Neil says that if you have done a ton of reality-TV shows, it might work to your disadvantage. "People are looking for a fresh face, somebody who hasn't been around," she said.
14. Know yourself and be proud of what you have to offer. "They need to know themselves ... know what their assets are … flaunt that. Own it," Monson said.
15. Looks do matter. It depends on the kind of show but, in general, "looks are very important," said Monson, who normally casts dating shows. "[It] would probably be No. 1."
16. If you're doing a reality-TV show because you want to be famous, casting directors can tell. Monson says she can spot the phoniness right away. "I have a pretty good eye. You can tell. You have the people who are desperate to be famous at any cost, and they will do whatever it takes," she said. "Sometimes they're good, but they also can kind of add an element of fakeness that we don't really like to put on the air, depending on the show."
17. Be persistent, but don't stalk the casting director. "On 'The Apprentice' we used to have people that would fly from city to city to city to try out and we're like, 'What are you doing?" Salyers said. "After awhile, we're like, 'We know who you are, buddy. We already have our opinion of you; you're not what we're looking for for our show." Salyers said some auditioners have reached out to him through his personal cellphone. "I'm always like, 'How'd you get my number?"
19. If you do get cast on a reality-TV show, be prepared for what you're signing up for. "Sometimes people are great in auditions and they make it all the way up through the network and they get cast on the show, and sometimes they can't handle it, and you see breakdowns on shows because of that," Monson said. "Sometimes people think they're getting into something and it wasn't what they expected. And so that is a reality check on a reality show."
20. Know where to audition and follow instructions properly. There are many websites that list casting calls and audition opportunities, such as: www.sirlinksalot.net, www.realitywanted.com and www.backstage.com. You can also apply via the show's website. "Make sure you send your contact information as well as good, recent photos of yourself, and explain why you would be a good candidate for the show," Monson said. "And of course, be sure to follow directions -- you'd be surprised how many people don't read the instructions!"
Scott Salyers is a reality-TV casting director who has cast shows such as "I Survived A Japanese Game Show," "Wipeout," "The Apprentice" and "Shark Tank." He also cast a new ABC show premiering in June called "Expedition Impossible," with Mark Burnett.
Sarah Monson is a reality-TV casting director who has been thrusting ordinary folks into the spotlight for years on shows such as "Blind Date," "Survivor" and "The Bachelor." She is penning a memoir about her career choice and how it helped her score dates. She blogs about reality casting at www.realityshowchick.com.
Sara O'Neil started her career, as with many casting agents for reality-TV shows, on "Blind Date" eight years ago. She did two seasons there and went on to cast a variety of shows including Bravo's "Millionaire Matchmaker," "Clean House" and a dating show on BET. She recently cast for a new Bravo show called "The Therapist," which is airing sometime this year.
ABC News' Susie Whitley contributed to this story.