Mark Lauterbach has a great post on Christian liberty on his blog. He says this is how we can apply Scripture in issues of conscience and liberty:

1. I look carefully at the decision to be made — if I am a husband I lead my wife and children in this. What is the issue at hand?
2. I go to the Bible, perhaps with the help of others or a good tool, and see if God has spoken on this matter with any single passage clarity.
3. If not – then I glean all the principles that seem to apply and pray them through and seek healthy counsel from others. I get counsel because I do not want my selfishness to be a motive in the decision. I can deceive myself too readily and make obscure what God makes clear.
4. I reach a conclusion — I will delegate the check book to my wife, we will home school the children, we will drink alcohol in moderation when served but we will not serve it to others, I will smoke a cigar occasionally, we will buy a luxury car, I will not get a tattoo, etc.
5. We keep our conviction to ourselves –we do not impose it on others or judge others by it — we seek to help others go through a godly process but not necessarily reach our conclusion — we respect different consciences and seek to do all things to build up those with whom we are present.