How to compete in a beauty pageant

Know what kind of pageant you are entering. All pageants are not the same. Different pageant "systems" have differing goals and criterion for winning. Though all pageant winners receive a crown, prizes and recognition, the reason behind the crown can contrast significantly. Look at former queens as a representation of what the pageant is looking for. What does this mean?
When a judge is scoring a pageant contestant, they have a list of items on their score card to rate. For some pageants, these items are strictly physical and the contestants are not required to have public speaking abilities or a specific talent. The judge will score items such as: body shape, facial beauty, smile, modeling ability, etc. These are TRUE BEAUTY pageants and are most often frequented by girls who are looking for modeling contracts, endorsement deals and cash prizes.

Other pageants, such as the local pageants which lead up to Miss USA or Miss America, focus more on internal abilities. Contestants are judged on their interactions with one another, on their interviews, public speaking skills, grace (as opposed to beauty) and ability to execute directions, under pressure. Physical beauty may impress the judges, but there is no beauty score. This is the case for the city prelims for Miss America and Miss USA.

Enter a pageant which showcases YOUR abilities. If you're not comfortable in a bikini, don't enter the Miss Hawaiian Tropics pageant. If you don't have a performance talent, don't set your heart on Miss America. There are so many different kinds of pageants, there's a good chance there's one for you.

2
Learn the rules and the status quo for the pageant you wish to enter. Attend the pageant, or a similar one, to see how it actually works. Preparation is everything for this kind of competition. Each pageant has it's own clear guidelines on what they are looking for and if you are able to follow exactly what they ask, you'll be eligible for high marks. For example, when I worked as a pageant judge, certain pageants had strict dress length codes, others weighed the personal interview heavily and not the talent and so on. Some pageant directors were very clear as to what kind of girl they were looking to crown-a beach body,a down-home fair queen, or someone versused on current events. Know what they are looking for. Get the down and dirty details so you can compete on a fair field. There's nothing sadder than a girl who shows up unprepared and sticks out like a sore thumb next to the other competitors.

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Learn where you can effectively break the rules. The winner of a pageant is generally the girl who distinguishes herself from the pack; she does something unexpected or courageous. For example, during one pageant that I judged, a girl chose to give her on-stage speech in 3 different languages. Each girl was given 60 seconds to complete her speech, but this information was not shared explicitly with the judges; we didn't know how much time they had. Girls who knew how to bend the rules elongated their speeches, like that girl who repeated hers in English, French and Spanish. Out of 50 girls, she made it to the top 10.

4
Spend some time with former pageant winners and/or trainers. Many former pageant winners, like myself, are commissioned to train new talent. It usually does not cost much, but it is worth the opportunity to hear an inside perspective. All of the girls that I trained made it to the finals, simply because they had a coach and understood that in actuality "they" were not being judged, their performance was. Trainers can help separate the fantasy of being named queen, with the practical skills needed to do it. They can help pick out your strengths and weaknesses when presenting yourself to the public.

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Don't expect to win your first pageant. Many girls competing in pageants have been doing so for a while. As in any sport or performance art, you aren't going to succeed right off the bat.
Although I won my very first pageant, at 18 years old, and was considered a "natural," I failed horribly at my next competition. I was just lucky that first time around and very unprepared for the level of competition on the next round.
Practice is important. Practice in the mirror. Practice in front of family who are able to give constructive criticism. Videotape yourself and watch all of the little twitches and awkward movements we all make. Practice with a friend who is also going to be competing and help one another.

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Always conduct yourself in a respectable manner. You never know when the judges are watching. Some pageants are very strict about cloistering their judges well away from the contestants, outside of the competition-others aren't. Although judges try to be objective, being human, they can be swayed and sometimes that's all it takes, especially if the competition is stiff. For example, in one pageant that I competed in, a contestant went to use the restroom outside of our dressing area, not knowing that a judge was inside a stall doing her business. The contestant made a quick phone call and used some foul language. The judge was not impressed and later admitted to me that it swayed the vote.

source:
http://www.ehow.com/how_4526289_compete-beauty-pageant.html