Cropped Cardigan

Black Cashmere Cardigan from Bebe

Avoid wearing the cardigan with a contrasting colored top beneath it (white with black) because it will make you look shorter and wider. Another way to make your torso look longer is to pair it with a solid, dark colored (black, dark brown, etc.) long top untucked. If you have a fleshy tummy you'll notice how the dark top will make you look slimmer around the middle as well as the cropped cardigan drawing the eye upwards and away you're your stomach. However if you have a long upper half you'll benefit by doing the opposite.

If you're full/wide on top

Then stick to dark colored and simple cropped cardigans to avoid creating a "cone"-shape frame. It'll slim them down. Remember that light colors/details highlight and expand! Another tip is to balance it out with an A-line skirt or dress, or flared jeans, anything that flares out at your bottom half.

Cardigan from Free People

Don't go auntie from top to toe.

Like for example if your cardigan is frilly and cute, try to balance the look with something casual and modern, or something opposite from the cute look. I love cross-mixing some sexy flair into something cute.

Like for example, if you want to pair a cropped cardigan with a grandma'ish vintage floral dress, then you should make sure that the hem is short to create a sexy-cute look (like the pic example from Free People to the right). Too much sugar won't necessarily lead to spice :/ PS: Try to add trendy accessories into the mix, such as a nice belt, gorgeous earrings, oversized cocktail ring or sassy high heel shoes.