Males usually have larger and more muscular shoulders than women, but there's something you can do to minimize them. Men generally hunch their shoulders forward, probably to emphasize their musculature and as a sign of aggressiveness. Women, on the other hand, tend to draw their shoulders back. Stand in front of a mirror and hunch your shoulders forward, then back. They will look noticeably smaller pulled back. This will also help your arms swing in a more feminine manner.
Females have wider pelvises and a higher fat distribution on their hips. This gives them the characteristic feminine swaying hips that's so attractive. Males generally have smaller hips and less fat in this area. Taking hormones will encourage female fat distribution on your hips and thighs [depending on what age you started and genetics], or you can wear padding. You want to give yourself the loose, swaying motion of the hips without looking put on. Female's legs swing looser from the knees. Walking in the classic female gait of putting one foot in front of the other will move your hips more, but again don't over do it. Find a compromise between the stiffer male walk and being overly-effeminate. Practice in front of a mirror and find a gait that's feminine, but not overly effeminate.
Women tend to slightly bob, or nod their heads from the chin, when walking. Men hold their heads stiffer with the straight-back, stiff-necked military posture being the extreme. Also, a woman's head pivots from the top of her neck, whereas a man's head tends to move more with his neck.
Don't continually look down at the ground or obviously avoid looking at people. This will tend to get you read since people will sense you're self-consciousness. One day while driving through town I saw what I thought could be a crossdresser, but wasn't sure as I was too far away to see any details. What gave her away was avoiding looking at people and looking down at the ground. If she had been walking confidently, with her head up, I wouldn't have read her so quick.
The purpose of passing is to not make someone pause and take second looks at you. Unless you're attractive and then it's a compliment!
Men are socialized to be aggressive and it shows in their walk. They tend to lean forward when they walk, probably in an attempt to get where they're going faster and push their way through crowds. Females are socialized for unaggressvieness and tend to yield and hesitate more when walking. Don't stride out in your masculine, aggressive gait. You're a woman! Hesitate more. Yield to people coming towards you. Don't be meek, but polite and yielding.
Glance at people's faces. If they look back you can gage by their expression how they're reading you. Smile. Nobody likes looking at a grump, whether you're a man or a woman.
Women and men smile differently, too. Men tend to have the classic wide, show a lot of teeth, nice-to-meet-you-businessman smile. Women tend to smile more with their lips closed, or just part of their teeth showing, especially when meeting strangers. Also, the sides of their mouth's are more upturned. Observe how women smile, in magazines and real life. Practice in a mirror until you see a woman smiling back at you!