How to Address Members of the Royal Family
On introduction and on leaving a bow or curtsy is made (see Addressing The Queen). Men should bow from the head only, and women should make a small curtsy. Neither movement should be prolonged or exaggerated. It is acceptable but less usual to shake hands.
Younger members of the royal family may not expect or want the deference paid to earlier generations. If you are expecting to be introduced to Prince Harry, or Princesses Beatrice and Eugenie, for example, it might be helpful to speak to their private secretary or equerry for guidance.
Anyone bearing the style and title of His or Her Royal Highness should be addressed as 'Your Royal Highness' for the first time, and subsequently 'Sir' or 'Ma'am' (to rhyme with Pam).