I’ve spent a lot of time with teenagers over the years, and without wanting to stereotype or say that all teenagers fit into the same category, I would say that generally they are trying to be accepted, to fit in and to know that people like them. (Perhaps those feelings don’t disappear when we leave the teenage years behind.) I have known a lot of teenage girls especially who have tried to impress people by the clothes and make-up that they wear.
I Peter 3:3-4 instructs us not to focus on external beauty, but on the condition of our hearts. This passage was specifically addressed to wives of unbelieving husbands, but I think that it applies to everyone. Our inner beauty will shine through as long as what we wear to enhance our outer beauty doesn’t speak more loudly. Peter was not saying that we should dress in rags and take no consideration of our grooming (because that would speak loudly too); he was warning against being outrageous and drawing attention to our physical features. I Samuel 16:7 tells us that people look at outward appearance, but God looks at the heart. It is our hearts that He is concerned with, but the condition of our hearts is displayed in our words and actions, including the way we dress.
I think parents really need to focus on open communication with their children and teaching them to be modest, sincere and pleasing to God. And they need to do it before the influence of the world tells them otherwise. Henry Winkler, as his character Arthur Fonzarelli, in the old sit-com Happy Days, once said, “I only got one thing to say to you Shortcake. You put out an advertisement, someone is going to answer that ad.” In Romans 12:1-2, Paul said that instead of selling out to the world, we should make our bodies a living sacrifice—alive, holy and pleasing to God.