Nuns, monks, priests, and some pastors have special garments, but ordinary Christians (laypeople) should dress modestly (but some Christians don't always dress as modest as they should).
Deuteronomy 22:5 A woman must not wear men's clothing, nor a man wear women's clothing, for the LORD your God detests anyone who does this.
1 Corinthians 6:19-20 Do you not know that your body is a temple of the Holy Spirit, who is in you, whom you have received from God? You are not your own; you were bought at a price. Therefore honor God with your body.
1 Timothy 2:9 I also want women to dress modestly, with decency and propriety, not with braided hair or gold or pearls or expensive clothes.
Also, Christians shouldn't wear tight clothes. Those are also indecent.
1 Corinthians 11:15 But if a women has long hair, it is her glory? For long hair is given to her as a covering.
Matthew 5:28 Whosoever looks on a woman to lust after her hath committed adultery with her already in his heart.
You can do you best to prevent that by not being purposely nude.
Swimsuits are about as modest as "short shorts". Christian girls probably can be more modest, by only wearing one around your family -- not boys (boyfriends).
Peter 3:2-5 Your beauty should not come from outward adornment, such as braided hair and the wearing of gold jewelry and fine clothes. Instead, it should be that of your inner self, the unfading beauty of a gentle and quiet spirit, which is of great worth in God's sight. For this is the way the holy women of the past who put their hope in God used to make themselves beautiful.
Also, inner beauty is more important the outer beauty. Sure, when you go out in public, you want to look nice. But if all you're focused on is how you look in the outside, Make sure you look beautiful on the inside too. :)
Christian boys probably shouldn't wear there pants half way down.
1 Corinthians 11:14 Does not the very nature of things teach you that if a man has long hair, it is a disgrace to him.