By beginning now to build your creditworthiness, once you turn 18 years of age, you will have some history of financial responsibility which will make it easier to get credit.
For now, look for ways to show potential credit card companies that you can and will manage your credit card responsibly. Having a debit card and managing it well is an excellent first step to show financial responsibility. Having a regular job is also a good way to show that you have income to pay for charges you would make on a credit card.

While it sounds like you already have a savings or checking account, using it responsibly is another important step to establishing credit. This means always having enough money in your checking account to cover the checks you write and depositing to your savings account on a regular basis to show that you can save money consistently.

Good luck in building your credit worthiness!