There are those that insist that what you wear on the outside is the first indicator of the state of your spiritual life or level of holiness on the inside. Arguing that if a change has occured in the life of a person, that internal change will be evidenced by the external change in that person's wardrobe and hairstyle.
So when someone decides to give their life to Christ, the first step they're taken through is the list of don'ts. Don't wear this, don't do that, don't go here, don't go there. Now, many of these suggested don'ts are actually good precautions to take if that particular person has had issues with certain areas. For instance, certainly to tell a drunkard, don't go to bars would be considered a good suggestion. After all, it is a fruit of the flesh we should all avoid.
Often the verses in I Peter 3: 3 Do not let your adorning be external—the braiding of hair, the wearing of gold, or the putting on of clothing— 4 but let your adorning be the hidden person of the heart with the imperishable beauty of a gentle and quiet spirit, which in God's sight is very precious, are used to argue that women in particular should not wear certain clothing or wear their hair in certain ways, or wear jewelry at all.
In a way, in doing so they make the focus of that verse what Peter is saying we shouldn't do. By learning to adorn ourselves in a certain way, doesn't make us any more christian, it actually only makes us learn to maintain appearances, or fool those around us, when the condition of our hearts and minds are not what they should be. And what good does pretending ever gain us, but a walk down a road to loneliness, lies, sadness or worse..
2 Corinthians 5:12: We are not commending ourselves to you again but giving you cause to boast about us, so that you may be able to answer those who boast about outward appearance and not about what is in the heart.
It is a much more daunting task to achieve a gentle and quiet spirit, and be so fruitful in the fruits of the spirit, that Christ shines through us in a crowd of people that look and dress similar to us. Dressing the part is easy, that's why we shouldn't make that our focus or the indicator of the condition of our spiritual walk.
Those critical first few steps of a new believers walk with Christ, should be an introduction to how each of us can be more like Christ in our acts, in our speech, and in our attitudes. And with maturing knowledge and understanding of Christ and his love for us, will come the convictions and designs for salvation that will lead to being a fruitful christian rather than a christian led to believe that maintaining appearances can actually earn them their salvation.