Inspire flattery. Enthusiastically compliment your woman's curves and voluptuous frame, style, confidence and personality while in the company of others. In doing so you will bring her the attention she wants and may not realize she deserves. Make your woman feel like the most beautiful woman in the room.
Validate her beauty type. In everyday conversation about movies and music and pop culture, be sure to reference and compliment other strong, confident and charming women of size This will send a consistent message that you appreciate her beauty type in general. Avoid just referencing the Hollywood or "standard" ideal of beauty.
Let your woman know that large is your normal preference. Explain that you believe voluptuous women are attractive, sexy and charming. Explain that you would not want a "skinny" girlfriend, for lack of a better word, and love every curve of her body. Assure her that she is perfect just as she is and should never be tempted to change for you or anyone else.
Purchase clothes that match your woman's style and general physical appearance. Demonstrate comfort with her size by buying lingerie and other apparel that is appropriate for her body as it stands today. Avoid purchasing lingerie or apparel she would need to diet to wear or be made to feel self-conscious in front of you or others.