At your age, i would get 1 credit card. Link it up auto pay to something, say your cell phone bill, and buy something you normally otherwise would buy cash (I.E Coffee in the morning).Then be sure to pay it off every month. (some people suggest that keeping a small balance is actually better, not honestly sure about that)
That will be a good start to building your credit, and won't put you into debt or anything scary because you won't be buying anything you normally shouldn't. Also you can set your limit low to protect yourself from the itch. Say 1k or something.