This isn't a perfect formula but Jerry Bridges does a great job helping us through Scripture see right from wrong. Keep these for Scriptures and questions close at hand.
1. Everything is permissible for me - but not everything is beneficial. (1 Corinthians 6:12)
Question - Is it helpful - physically, spiritually, and mentally?
2. Everyting is permissible for me - but I will not be mastered by anything. (1 Corinthians 6:12)
Question - Does it bring me under its power?
3. Therefore, if what I eat causes my brother to fall into sin, I will never eat meat again, so that I will not cause him to fall. (1 Corinthians 8:13)
Question - Does it hurt others?
4. So whether you eat or drink or whatever you do, do it all for the glory of God. (1 Corinthians 10:31)
Question - Does it glorify God?
This formula can be found in Jerry Bridges excellent book The Pursuit of Holiness.
Grace upon grace,