I'm probably not the best to answer this since I feel like the opposite is very hard for me to portay. But I think it's all in the mind first, then body movements. For instance, walking with feet pointing forward, with smaller steps. It helps to emphasis hip movements. You can even look down when you're practicing your walk and your hips and bum should slighlty twist (but not in an uncomfortable, awkward or obvious way).
General mannerism are being more graceful like picking things up ever so gently. Lol I'm very clumsy so it actually helps me a lot when I slow down and the real grace comes through somehow.
Take your time and have fun! Crossing your legs is fine but also slightly pushing them together and bending them a bit to the side I find is very feminine too. Hope these are helpful!
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