I'm a 12 or Large generally. Sometimes a medium, because women's sizing standards seem nonexistent. My ideal size is the one that accentuates my curves the best. My only problem with sizes, is that anything 14+ and XL start to get very loose in the waist and not give me any extra room in the chest.
My favorite part of being a woman is the challenge of remembering all my sizes. 3 different pants sizes, 5 different dress sizes, 3 different shirt sizes, 2 different bra sizes, panty size, those ever changing shoe sizes by style, and jackets. It's a great tool to keep your mind sharp!