A retail CEO reveals the simple work wardrobe rule she thinks everyone should follow

Sarah LaFleur is the founder and CEO of MM.LaFleur, a clothing brand designed specifically for professional women. LaFleur, whose sold-out dresses have at times amassed a 1,600-person waitlist, has a great rule of thumb when it comes to shopping and purchasing clothes for work - and the rule can apply to both men and women in the office.

She calls it the 40/40/20 rule.

"Our 40/40/20 philosophy centers around the idea of building a balanced wardrobe," LaFleur told Business Insider. "As a general rule of thumb, we think an ideal work wardrobe is made up of 40% everyday pieces, 40% elevated pieces, and 20% showstoppers."