One of the best practices you can engage in with respect to getting credit worthiness established is to have a single card and purchase on the card only what you know you can pay off at the end of the month when the bill becomes due. A regular pattern of paying on time and in full will put your credit score in very good standing.
I typically only use a credit card, now anyway, for only large purchases such as vacation travel, or home repairs/upgrades, etc. And at that it's after planning the budget accordingly so that I don't suffer from budget shock. Impulse purchasing on the credit card is a major no-no. Limit shocks to your budget by avoiding temptation to use the magic card.
On the subject of budgets if you don't have one then shame on you. It's a good practice to build a budget even as a college student with limited income.
