The tango walk is done by two partners chest against chest in the embrace. The man walks forward, the woman walks backward, and they must walk with matched CBM, dissociation, lilt, rhythm, posture, etc., in perfect coordination, balance, harmony and elegance. Many students cannot walk well because they don't have the needed muscles, flexibility and techniques, their legs and feet are too weak to maintain balance and stability, their postures and habits are not up to the standard of tango, and their personal praxes conflict with each other, causing disharmony and instability in the walk.
There are more exercises in tango designed for women than for men, just like there are more fashionable dresses, shoes, jewelry, and cosmetics designed for women than for men. Which is not surprising given the importance of beauty to women and the fact that, while men lead women in tango, it's women who beautify the dance. (See The Gender Roles in Tango.) How women walk, therefore, matters more than how men walk in tango.
In order to walk well, you first need to develop muscles that enable your feet to suck the floor and stay very grounded in the walk. Dancing a lot certainly helps. Exercise and workout can also be beneficial. One exercise that I found particularly helpful is demonstrated by Vanessa Gauch in the following clip.
In tango, women mostly walk backwards, which is difficult because that is not how people normally walk. To learn to walk backwards, you almost need to start from toddle. The following clip, demonstrated also by Vanessa Gauch, can help you understand how it should be done.
Walk backwards in leaning position
It is important to point out that the embrace affects the walk significantly. Walking in an A-shaped frame is very different from walking in an H-shaped frame. Women using open hand holds in the dance cannot stretch their leg back far enough, because without leaning on the man it is hard to keep balance on one leg while outstretching the other leg. Here is an example.
The two teachers are competent dancers, I believe, but the H-shaped frame they used in the exercise hampered their performance. In comparison, walking in close embrace, or an A-shaped frame, is much more stable, balanced and elegant, as illustrated in the following example by Jennifer Bratt and Ney Melo.
Good tangueras all use the hip to move the leg, without exception. Here is another excellent example, danced by Mariana Montes with Sebastian Arce.
Keeping your own balance is the key to be weightless
As comfortable as it is to lean on your partner, you need to keep yourself light and not become his burden. This means you have to keep your own balance by bending your standing leg when you stretch your free leg backwards, as explained by Vanessa and illustrated by Jennifer and Mariana, so that most of your weight is carried by your standing leg rather than on him. This will also allow you to outstretch your free leg farther. Personally I found that when a woman leans lightly with her chest rather than heavily with her stomach on me, she becomes lighter.
Improving your walk is the key to improve your dance
I hope these illustrations would give you an idea of how to walk in tango as a woman and help you to improve your walk. Walk is not only an important part of tango, but also the foundation of the dance because other steps are but variations of walk. One's walk defines one's dance, as demonstrated by my favorite tango couple Noelia Hurtado and Carlos Espinoza in the following tango. Pay attention to Noelia's walk and see how it relates to her other steps. For a woman, beautiful walk is a guaranteed eye catcher and proof of her ability. By learning to walk elegantly, your tango can be improved in more ways than you can imagine. (See Walk.)