Basically you have to play the game. As long as you make the payments and don't pay it off too quickly then that will show that you are good at making payments consistently. Also, if you completely pay it off after some time then that will help too. The more you have (that you can take care of) the more your credit will go up. However, if you miss a payment or something then your score obviously will go down. Also, be careful not to have too much debt because even if you make payments consistently and make enough to take care of your expenses, it will still lower your score. Example, I did a refinance loan for a guy with about 1.5 million still owed on his home and his score was lower because of his debt. He made payments just fine but his debt was too great. Now if he pays off some of that then he will be back into the high 700's.
Realistically you can get a loan with a 600 credit score, but your rates and fees will be high. If you can get your score close to 680 or above then you will get a decent loan with decent rates and fees. Into the 700's and you can pretty much get what you want depending on your income.
It's good to see someone concerned with this at a younger age. Most people don't start thinking about this until their 20's or are out of college. Good luck to you!
6 years in the business