With Balmy Weather just around the corner and with it the itch to look sharp, we've taken this year's spring-and-summer fashion forecast and separated the clothes into three distinct looks: tailored, easygoing dressy and casual. It should make your wardrobe selection a lot simpler. Remember that tailored clothes are a significant investment, so you'll want to make your choices carefully. The smart money this season will be on double-breasted jackets with wide peaked lapels and soft, sloping shoulders and multipleated trousers that drape. Dress shirts will echo this casual mood with soft, straight collars. Neckwear will remain wide, three and three fourths inches being the maximum. (At left: A wool six-button suitwith double-pleated trousers, about $1250, worn with a striped cotton shirt, about $130, and silk crepe de Chine tie, about $75, all by Er-menegildo Zegna.) When it comes to easygoing dressy--that relaxed but stylish fashion zone between tailored and casual--the two stalwart choices remain blazers and sports jackets. This year, both double-breasted styles and the traditional single-breasted three button are the favorites. They often look best when combined with a tieless shirt and khaki trousers. (Worn with a pair of walk shorts and a polo shirt, they become a shorts suit, as seen at right, which includes a three-button linen blazer, $355, pleated plaid linen shorts, $100, both by Andrew Fezza; and a cotton knit polo shirt, from Basco by Lance Karesh, $52. Sunglasses, by L. A. Eyeworks, $125.) For the casual look, there'll be plentyof vested interest in vests this year. What could be more casual than a sleeveless jacket? (Below left: A cotton floral-print vest with antique-style buttons, $125, triple-pleated cotton walk shorts, $100, both by Paul Smith; and a linen sport shirt, by Kermit Smith for Krunch, $180.) Other choices include loose-fitting, tropical-print camp shirts and lightweight, brightly colored jackets. Follow our advice, guys, and you'll be making all hits and no misses all season long.