MICE HELP

I need advice. I have noticed and heard a few mice around my house. We have killed a few but they keep coming back. My house isnt messy but its not perfect. Sometimes dishes dont get washed for a few days but there isnt like food left out or anything. I cant afford an exterminator. And they are getting pretty bad. I can sometimes hear them in the ceiling or walls. My house is kind of cluttered and I know they like to hide behind shelves and toys. Im at my witts end. Ive tried peppermint spray and oil. Im going to buy some traps when i get paid but what else can I do?