Make sure you do something about your bad breath tomorrow.
You should try to figure out a way to get rid of your bad breath tomorrow.
この場合、次のような言い方ができますよ。
ーMake sure you do something about your bad breath tomorrow.
「明日、あなたの口臭どうにかするんだよ」
ーYou should try to figure out a way to get rid of your bad breath tomorrow.
「明日、口臭を消す方法考えなよ」
bad breath で「口臭」と言えます。
ご参考まで!