Well, don't do what I did. My SO gave me pointers on how to walk like a guy and I looked like John Wayne who'd been riding his horse for three days straight. It was way too exaggerated, so much that my SO and I both laughed out loud. lol
It worked better when I kept my body the slightest bit more rigid and parted my legs a tiny bit more, like an inch.
And just so as not to misconstrue myself, I'm not FtM but was wanting to experience the challenge of adopting mannerisms that are not natural to me.
... oh, and the link below is pretty good. It's an animated walk model by Biolabs that you can slide between the two genders to see the differences. The mistake most people make is to believe they must walk waaay at either end of the scale, which is what makes it laughable in real life. Most people walk someplace in the middle, or slightly to the right or left of the middle.
Click on the "Lines" radio button at the bottom to see the walk more clearly, and there are also walks that reflect different moods:
http://www.biomotionlab.ca/Demos/BMLwalker.html