What can I do with my money to get more at age 18?

So let's say I save every dollar I make as soon as I turn 18 and get a job. And I save my money and let's say its 15k I have after a year. What can I do with that money and if 15k is too little to do anything with how much is a better number and what can I do with it? I'm talking anything anything as long as it gets me more in the long run. Btw I'm going to college too so don't say just go to college and college expenses aren't an issue.