Sparkling tinsel and garlands are December decor staples, but when it comes to gussying up your store for the holidays, they could be doing you more harm than good.While decorating may fall at the bottom of your to-do list during the busiest sales period of the year, it merits careful consideration. A store draped in tired-looking trimmings can actually turn off shoppers. Conversely, a clean, contemporary scheme has the power to lure in potential buyers. Shoppers delight in creative holiday displays, and how your store looks during this crucial time directly affects how it will perform.“You can’t just plop down an old tree and expect it to look fresh,” says decorator Allyson Paris, owner of Allyson Paris Designs in Fair Lawn, N.J.A fan of posh-looking holiday design elements such as mirrored trays (for champagne!), boxes wrapped in metallic paper, and vases, Paris recommends that r