There are oversized T-shirts and tight T-shirts, bare T-shirts and long sleeved T-shirts, one-shoulder T-shirts and scoop-neck T-shirts. And now that many people own a great variety of them in several colors, the fashion industry, typically, is trying to lure women into wearing something else. The alternatives are tempting - peasant bluses, camp shirts, camisoles and others. Among the options in Washington stores: CAPTION: Illustration 1, The peasant blouse with eyelet ruffle - can be worn tucked in or left out, from Elles Belles at Woodward & Lothrop, ($23).; Illustration 2, Boys tuxedo shirt with pleated front from Black Tie Formals, ($14).; Illustration 3, Embroidered camisole with drawstring waist from Mexico has a matching coverup. From Georgetown Cotton, (camisole, $14, jacket, $33.50).; Illustration 4, Calvin Klein's silk camisole can be worn with skirt or pant, in champagne color from Elizabeth Arden ($100).; Illustration 5, Faggotting and embroidery decorate the yoke of a natural color blouse from Ellen Tracy, at Mardi's Boutique ($28).; Illustration 6, The pullover camp shirt in bright orange, blue, red and yellow, in ployester cotton by Chaus at Woodies, ($14).; Illustration 7, Cachahel's demure white cotton blouse with scalloping and white-on-white embroidery from Garfinckel's, ($46)., Illustration by Martha Vaughan for The Washington Post