If you were trying out for something like dancing, singing or sports maybe, then you should STAND OUT. That is your only chance. You can be not the best on that audition or tryout but still you have to let them see what hasn't seen before. You have to wow the judges or the picker so you will have a bigger chance of getting picked.
A lot of tryouts nowadays has also something to do with politics. Many people were just picked because they have a backer or they were connected to the one who is choosing the applicants. But you shouldn't make that as an excuse. There are many ways to catch attention and that is separating yourself from the pack. You may not be the best but if they see something in you that wasn't seen before... then you can also succeed.
For example in basketball, if you are not that tall or athletic and you also don't have a backer... you must have something that can catch their attention. It can be insane dribbling skills which can be achieved by practicing everyday or very sharp shooting skills which can also be achieved by practicing hundreds of hours. There is no excuse for you not to be picked, the only reason why you haven't been picked is because you've been lazy from the past and you didn't hone your craft.
In singing, if you don't have the nicest or highest voice then you should think something that can touch them. It can be singing with all your heart, when I say with all your heart it means you don't have to follow the traditional way of singing, you don't have to be technical, you will use your own style and you will not be afraid if you will fail. It's like singing fearlessly and singing for yourself. Don't sing for the people or else you will not be able to reveal your true and unique identity.
I know you can show something that wasn't seen before because all of us has his own unique set of skills and abilities, all you have to do is have the courage to express your true identity and do something with all your strength and tenacity.