Assisted by Kathleen Sterritt 120: Here's the lowdown on boots this season. Wear them low down on the leg, pushed down when possible, and layer the leg with socks and hose of many textures and colors to achieve the messy, casual effect appropriate with many of the new clothes. This look swept in with the oversized, darkened clothes of Japanese designers that American and European designers have emulated and balances the proportion of these supersized clothes. CAPTION: Picture, Kenneth Cole's black leather boot with furry sweater top at Woodward & Lothrop ($72); cotton- knit ankle warmers with black edging by Hue ($4.50) at Klein's 4 Seasons; underneath, charcoal knee highs ($4.50) by Hot Sox at Woodward & Lothrop. Gray leather lace-up boot by Thom Brown ($75) at Georgetown Leather Design; gray cotton/polyester socks ($4) by Burlington at Hecht's; gray socks with black dash by Ditto ($4.50) at Klein's 4 Seasons; gray ankle socks with white dot by Burlington ($4.50) at Les Gals. Ankle-high black boot with snaps and zippers ($80) by Free Time at The Bootlegger, worn with Burlintgon's tweed nylon tights ($7) and Electric Sox tan and black-dash-patterned cotton sock ($6), both at Hecht's. Suede and leather lace- up boot ($90) by Unisa at Garfinckel's (F Street); blue-green flecked short sock ($7) and gray and black tweed patterned sock ($7.50), both by Perry Ellis for Trimfit at Bloomingdale's. By John Bowden