I'm currently taking a children's literature class in college, so I'm reading tons of stuff.
This week I read Because of Winn Dixie, The Boys Start the War, Just Juice and Hatchet.
Winn Dixie and Hatchet were my favorites out of those... they are something you probably read in fifth or sixth grade. Although I'm in my thirties and enjoyed them... I laughed out loud reading The Boys Start the War.
Have you read any of Madeline L'Engle's stuff? She's awesome. My favorite books at about your age were The Wrinkle in Time series. The second book is A Wind in the Door and the third is A Swiftly Tilting Planet. My daughter is 15 and she loved them too.
Around 13 or 14 I was also reading Anne Rice's vampire books and anything Stephen King that I could get my hands on... :) still an obsessed King fan today.
How about The Life of Pi? About a young boy trapped in a boat with a tiger.
What kind of stories do you like? Fantasy? Realistic fiction? Historical fiction?
It's absolutely fabulous that you're asking about books. Reading is the best thing that any of us can do to improve our chance of success at anything... unless you golf like Tiger Woods, lol.
Good luck to you, hope you find something engaging.