It is true that the Bible tells us to dress modestly and that our true beauty comes from within, not from outward ornamentation (1 Timothy 2:9). But these verses are not saying that nice clothes, jewelry etc. are sinful in themselves. Keep in mind that Jesus wore a seamless robe, which was a very costly garment (John 19: 23-24). When Joseph went to meet with the Pharoah, he recognized that the proper ettiquette involved dressing in a respectful manner (Genesis 41:14). Furthermore, Proverbs 31:22 describes the godly, virtuous woman as wearing clothing of silk and purple.
Those who claim that women should not wear pants base their concerns on Deuteronomy 22:5: "The woman shall not wear that which pertaineth unto a man, neither shall a man put on a woman's garment: for all that do so are abomination unto the LORD thy God" The principle certainly applies in that a man should look like a man and a woman should look like a woman, but keep in mind that in Bible days men and women both wore robes. They were simply cut differently. In our day, pants are distinctively designed to fit either men or women, so they can easily be worn without confusing or compromising gender identity. Similarly, some discourage Christian women from wearing makeup because it was worn by the evil Queen Jezabel (2 Kings 9:30). However, reading this passage in context shows that the problem was not simply in Jezabel wearing makeup. Rather, it was because of the wicked, idolatrous life she lived. It is noteworthy that Job had a daughter named Keren-happuch. Interestingly, this name means "horn of eye paint." Would one of the greatest men of God in the Bible name his child after something he knew to be sinful? As one minister humorously put it, "A little paint never hurt any old barn."