A natural female walk can help your passability and compensate for flaws in your appearance.
Either walking in an overly-effeminate manner, or in a stiff male walk, will tend to make people stare at you and increase your chances of being read.
How do you develop a natural female walk? Practice. Unlearning your male walk and developing a female walk may take some time. Females have had all their lives to be socialized in being feminine, so by the time they're adults it comes naturally. Also, their bodies are put together differently and move differently. Strive for a naturalness that you don't have to think about.
What is the essence of the female walk? Go to a place where there are lots of people and observe how women walk. How her arms and legs move. How she carries herself. How she holds her head. Your goal is not to invent a totally new walkthat will look unnaturalrather integrate a feminine style into your own gait.
Women have naturally looser bodies. This is probably due somewhat to less muscle mass than males, but also to evolution. Females, being the child bearers, need a more flexible body to accommodate the changes her body goes through during pregnancy and childbirth. Women's forearms are connected at their elbows at a more obtuse angle than males, so they swing farther out and don't hit their wider hips when walking. You can accomplish this by putting your arms down at your sides and rotating your hands 45 degrees away from your body, so your forearms face forward. This will allow your forearms to swing out in a more female manner. Curl your fingers up into your palms when you walk.
When standing still, and sometimes when walking, women tend to hold their arms above their waistline. This is the typical female way of holding one's arms and is the main difference in how men and women hold their arms. However, this can look too effeminate if you walk all the time with your arms above your waist. If you carry a purse, try holding onto the strap with one hand and let the other arm swing free. Allow your arms to swing freer from where they join your shoulders.
When you rest your hands on your hips, rotate your hands so your fingers are facing backwards and thumbs forward.
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.