Jesus fought with the Word of God. When the Devil attacked him, the first words out of Jesus' mouth were, ‘It is written...’
As a Catholic, you have to have a Bible and you have to read it every blessed day. Learn Sacred Scripture by heart. When you are tempted, say to the Devil, ‘It is writtern...’ God's word is powerful and alive!
Use the weapons given to us. Especially, God's word.