For many interior designers , moving to a new home is an excuse for a shopping spree. But not so for Michelle R. Smith . Over the years, as the seasoned decorator has migrated from Manhattan to Brooklyn or Brooklyn to New Orleans , she has always packed up her favorite things and redeployed them as dynamic vignettes in fresh contexts. “I don’t obsess over anything—I just know it’s gonna work out,” Smith says of her personal and intuitive process. “ I’ve designed enough spaces for myself to know everything will find a place. I don’t even do a furniture plan. Just move it all in.” Smith accented the entry’s existing masonry walls with custom millwork. The vintage pendant lamp was a lucky find on eBay , and the terra-cotta floors are original to the house. Alan Lewis That is not to say she hasn’t picked up some new tricks—and yes some new treasures—along the way. Take her home in Westchester County, a case study in pastoral romance, clever fixes, and reinvented traditions.…