Awesome idea. I got one when I left for college when I was 18.
If anything, it builds your credit score.
If you think you are responsible enough to have one and avoid unnecessary charges, I would get one. They are great to have if an emergency happens. For instance, I haven't really needed it for that reason until this past December. I was driving home from working the weekend at WDW and my car window broke. Some mechanism in the door broke and the window wouldn't stay up. It cost like $400 to fix, and while I had the money, the credit card made it easier to pay for.
Just try not to let it get out of control. Three years ago I bought a bunch of concert tickets and it took me a year and a half to pay it off.