So let's get down to the fashion and how you can recreate their looks for less.
Taylor Swift wore a brightly colored maxi skirt paired with a contrasting brightly colored crop top. To achieve a look similar to hers, try sewing the BurdaStyle Inverted Maxi Skirt and insert the slit, depending on the pattern. For the top, sew up Phuong's Cropped Bustier Top. It looks a bit long but you may be able to shorten it to your desired length.
Carrie Underwood wore a long strapless black dress with a sexy thigh high slit. A similar look can be achieved with this McCall's pattern. If you're an experienced sewer, you can tweak it to achieve the feathered bra cups and gathered fabric above the slit.
Meghan Trainor wore a sleek, sparkly gown with a knee length slit in the front. This vogue pattern is similar with the exception of the slit and v-neck.