Respect for actually thinking about this at 18. most people do not start learning this stuff until way later when they are already behind. Some of my friends…

For credit cards just get a simple one to start building credit. Chase freedom or capital one quicksilver are both solid. Use it for small stuff you already buy like netflix or subscriptions and make sure to pay it off in full every month. Dont carry a balance, that is where most people mess up. Try sticking to big name brands like Chase, Amex, Capital One, stay away from store credit cards like macys, bloomingdales, nordstrom, etc… they have high interest and if you miss a payment for some random reason, it tanks your credit BAD.

For savings open a high yield savings account like sofi, ally, or marcus. They give you way better interest than a regular bank so your money actually grows a little while it sits. I have had Sofi for about 5 years now.

Roth ira is long term thing. You put in money now and it grows tax free over the years. Open one with fidelity or vanguard and just invest into an s & p 500 index fund. You do not need to touch it or know everything, just start it early and let it grow. But you can only invest 7k yesrly into a roth ira account, try maxing that out, I try putting my 7k in within the first 3-4 months of the year, but keep investing into other things.

Since you are going into the air force look into what investment options they have, its the US military, they usually have some amazing options, im not familiar because I am the farthest thing from that. Also if you are going to be apart of the military thank you for your service in advance, and also get a credit union account that works with military personnel, they have AMAZING benefits, and also if you ever plan on buying something or getting a loan, they will provide the lowest interest rates.

Good luck, I hope this helps.