Sit like a royal
One of the worst things a woman in the royal family can do — as far as etiquette rules go — is sit with her legs crossed at the knee. Legs and knees must be kept together, although crossing at the ankle is fine. One popular pose is called “the duchess slant,” coined by Beaumont Etiquette and named for the Duchess of Cambridge, Kate Middleton. Her go-to sitting position involves keeping her knees and ankles tightly together and slanting her legs to the side. It keeps her posture modest and makes her legs appear longer. In fact, the late Princess Diana was known to sit the exact same way.
Sources: Business Insider