Start with a polyester base. Betty's wardrobe staple is definitely polyester. Luckily, a quick raid on a "vintage" clothing outlet (otherwise known as the Salvation Army) will provide you with a treasure trove of Ugly Betty prints. Look for shapeless blouses and dresses that poof where they should pull and pull instead of poof. Just remember that the key to your Ugly Betty polyester success is 1970s color.
Add a mismatched vest. While a vest is not an Ugly Betty fashion necessity, it is part of Betty's trademark look. A knit vest in a color that makes you think of 1970s car paint or shag carpeting is a perfect find for the Betty outfit. Make sure that the vest is a bit big and saggy and that it is an absolute color clash with the polyester blouse or dress underneath.
Put thick-socked feet in clunky shoes. Closed toe pumps are the way to go to achieve Betty's haute couture kitsch. You can choose the color basically at random, just make sure that the pumps are big and clunky and that you're wearing them with socks.
Accessorize Betty style. Nothing says (or maybe screams) Betty like a big "B" necklace, glaring eyeglasses and an oversized leather purse. A trip to an antique or thrift shop will give you an arsenal of Betty-style accessories to hang, hold and clip. Don't be afraid of a brooch or pin and remember that if you need advice just ask yourself, "What would Betty do?"