I remember when I first started to wear vintage things, and I was nervous about it. So here are a few tips. Don't go totally vintage, use a vintage piece here or there, and use quality items. If buying second hand makes you nervous, just go shopping for those things out of town and no one will know where you got it. If anyone asks, you can say a relative gave it to you!
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Have a teenaged girl who longs for expensive mall fashion? Tell her that a current hip fashion trend is making over vintage t-shirts. There are whole stores in L.A. devoted to made-over vintage tees!