How to win an art contest
There is certainly no easy answer to this question. However there are some guidelines to be observed in order to become successful. First of all have a look on the open calls of the moment. The competitions defer concerning the kind of art they attract. Have a look on previous finalists and winners. If you consider their art similar to yours or, because yours is certainly unique, you think you are working in the same genre of painting or photography, you have found the right place. On the other hand, if you think the jurors must have been drunk to award prices to these pieces of sh.., then go someplace else. To qualify art as good or bad is naturally a matter of taste, but there are contests, where the jurors prefer highly avant-garde artwork, which possibly need to be explained to be recognized as art, and others, who also still give a chance to figurative and even to traditional genres of art, those who not only valuate the idea, but also the content, the expression and the craftsmanship, in other words the over-all impression of the artwork. Therefore you should be careful with contests, where the presented works are not shown on the website. You could be surprised with the results of the jury.
Once you have chosen the contest, you think your art would fit, then consider presenting more than one piece. With only one piece it is quite difficult for the jurors to evaluate your work. It is often the case that the only work you present is not considered to end up a winner, whereas they would have considered another one as far better. Jurors read your profile and definitely have a look on your website and maybe find that you should have presented another piece of art.
The next possibility to impress jurors is to be persistent. If you do not succeed to be a finalist in the first edition, continue with the second and more. The fact that you are not amongst the finalists in one edition, really does not mean that your art is considered to be bad by the jurors. Imagine, maybe all the presented art is outstanding! Jurors also change with the next edition. There is no reason at all to be offended if you do not get the first price with the first attempt! Jurors are fighting hard with themselves during weeks, if there are unsure which work to prefer. Look at the different contests and you will see, that artists participating every year one day will succeed.
Now some advice on what you should not do. Do not send your artwork by e-mail before you register with the contest asking if they would like it! They would not give you such answers, as the decision is made by the Jury and not by the organizers. In the same way, do not just create your account and leave it alone without creating a complete registration and participation in the contest. This is a waste of your time and nobody would consider you. You only will receive loads of mails reminding you to complete your inscription. Finally do not present the same piece of art to many contests, although if you consider this very piece as your masterpiece. The Juries would think you only have this one, and in the worst case you could not show it at several places at the time.