Do take a lesson from Mary Kate (for once!) and balance out your proportions. If you're wearing something loose fitting on top, break out a pencil skirt or skinny jeans and boots on bottom. Conversely, if you're wearing wide legged pants, opt for a fitted cardigan or blouse on top as opposed to a blazer or baggy jacket.
Don't make the mistake of buying into a trend if it's not flattering on you. I'm sure Rebecca Romijn simply thought, "Stripes! Hot!" when she chose this dress, but I'm left with, "Circus! Clown!", which is probably not what she'd intended.
To read the rest of "Style Do's and Don'ts From Our Friendly Celebrities!", head over to Lindsay Ferrier's new column at The Stir by CafeMom.