I've logged about a jillion hours out and about en femme, usually a couple of days a week, out in the regular world, day and night. Hopefully, I've learned a thing or three...
Here's my distillation of what really helped me get it. Try it and see if it works for you.
There's two parts: What not to do and what to do ...
Don't: roll the shoulders left to right -- they should stay level and even. You should be able to balance a book on top of your head as you walk. Your shoulders in a femme walk are back and you're standing straight.
Don't: spring off the toes of your feet.
Do: The swivel: learn to isolate your hips, so that you can (if looking from above), swivel the left forward, then the right hip forward, a little like doing the twist. Do while standing still. The shoulders and feet are still, only the hips rotate. Your skirt should fan out, as you rotate clockwise, then recenter, then swivel counter clockwise.
It takes practice to feel natural. When you've got this mastered, your half way there.
Do: The tilt: learn to isolate the hips so that you can move the left pelvis up, and the right down, while being stationary. Nothing else moves, just the hips.
Bonus: You get some dance hip moves for free! I remember a woman pro dancer telling me when I complimented her on the dance floor "It's all in the hips!"
Do: Learn to move both hip motions together, the swivel and the tilt. When you can freely move your hips using both motions without thinking, and your upper body remains still and relaxed, then you can ...
Walk: Start with a swivel to the right and slight tilt up as you lift your left leg -- that's what leading from the hip is about. The push off from the back foot is subtle and gradual -- the driving force for each step comes from swiveling hips a bit as you move the front leg forward.
With a subtle back-foot push, your strides are shorter, so you have more steps to feel and learn the hip-swivel as you bring the front foot forward.
If you throw a lot of swivel/tilt as you step, you're advertising more If you use just a subtle swivel/tilt as you step, you're toning it down, but it's still unmistakably feminine.