>>81893784 (OP)How much cash we talking?
Are you currently in school or pursuing a career? In training to get a career?
Get a secured credit card. Sure, you should aim to avoid getting into massive debt that you can't pay off, debt with high interest that keeps you in debt, but a secured credit card is a way to start building credit while you're 18.
You give a deposit which acts as your line of credit and you keep the spending under 30 percent, pay off your balance in full before the due date, and aim to keep the balance on the statement date under 30 percent so it'll look good on your credit report. Credit is your documented history of managing finances. The better you are at not overspending and paying off your debts on time, the better your credit score, the better your interest rates when trying to finance a car or get a mortgage for a home or rent an apartment. Some jobs also run credit checks