Get a job

Colleges love an applicant who's had a job.  And it doesn't have to be a fancy-sounding internship at your mom or dad's company.  Colleges–and future employers–are even more impressed by real, honest teenage jobs, like flipping burgers or coaching basketball or selling clothes at the mall.    

Colleges know that it takes initiative and responsibility to find and keep a job.  Look up the biography of a successful adult you know, and you're likely to find jobs in their past before and during their college years.

Today, Mark Cuban owns the Dallas Mavericks, but when he was a kid, he sold trash bags door to door to make money to buy a pair of expensive high top shoes he wanted.

When he was in high school, Zappos
CEO Tony
Hsieh
ran the lights at a community theater, then became a game tester for Lucasfilm, then worked as a computer programmer.

When she was seventeen, Maya Angelou worked as the first black female streetcar conductor in San Francisco. 

During high school, Supreme Court Justice Sonia Sotomayor worked at a bargain retail store in
the Bronx and at the local hospital.

Sherwood Rowland won the Nobel Prize in chemistry in 1995 for his work identifying the causes of ozone depletion.  He spent portions of his high school summers running the local volunteer weather station, a job he cited as "my
first exposure to systematic experimentation and data
collection."

So if you're looking to learn, make some money, and impress colleges, get a job.  And someday when you're a big success, you'll have a great story about your first job back in high school.