Three main elements will help your admission chances:
1) Strong essays: Be honest, thoughtful, and creative.
2) Extra-curricular involvement: Pursue your passions! Be active and make a difference in your community. Do what you want to do, not what others want you to do. Explain on your application what you wanted to do, why you wanted to do it, and the actions you took to get there.
3) Teacher recommendations: Develop meaningful relationships with teachers. This will help you when you need to ask that teacher for a recommendation.
Hope that helps and please feel free to reach out to me with questions or concerns! Please email me at Go Blue!