credit score???

okay, so i just REALLY want a higher credit score 😫 i feel like i stress about it waaay more than I should and im not really sure why lol. So I'm 20 years old, I really dont have a lot of credit history. I do have a car in my name, and I also have a few credit cards. I pay everything on time. My balances on my cards are actually pretty low, but could be better. I'm in the "fair" range on credit karma, as of right now, but I would like to be in the "good range" lol. How do i raise my score, does it continue to raise over time if I still have the same accounts, without adding more, and they're all in good standing, and about how long does it take to see a significant change in your score????