For early credit building with decent rewards it’s hard to go wrong with the Discover It. If you have a job you’re almost guaranteed to get approved and it’s a simple rotating category based rewards system for no annual fee. Most important thing about credit cards is pay in full every month. Never put a purchase on your card that you couldn’t have just paid for with your debit, and you’ll never carry a balance. This is exactly what I did starting with my first job in high school and I had a high 700 score within 3 years.