What to do when vet says cat has tarter and gingivitis?

So I just took my new cat to the vet for the first time (for me taking her), and she got a healthy report, except for the teeth. I just looked up the symptoms for gingivitis, she doesn't have any of those, so, I guessing it's not bad or anything yet. It costs too much to get a teeth cleaning, money I don't have, as I'm a college student. Is there anything I can do to make sure it doesn't get worse, and to possibly make it go away?