For silent walking, use polar fleece as clothing, or something very soft (some hunting clothes are made with some special cotton fleece that is very silent too). A lot of the noise we produce is made by our clothes, when moving or when coming accross vegetation. Cheap phys ed pants and sweat shirts are also great for that. Jeans are not good. US BDU pants are not good either (too much polyester in them, any friction will be noisy). The canadian uniforms are made with a fabric that offers only cotton to friction (even though there is some sort of a nylon mesh under it). They're pretty good, and the new relish-like camo is nice too

. Of course, forget about nylon, gore-tex liners or other synthetic fabrics...
Move very slowly. Breathe calmly, be totally relaxed. If you're stressed or if you have too much tension in your movements, you will be too stiff to make soft and slow movements. Of course, it's often very tough to be relaxed when you see a huge buck only a few steps away from the reach of your bow... be patient. It won't work otherwise anyways. Nobody can walk fast AND silently in the woods.
Some animals (and humans too) seem to sense when you look at them. Just don't look at them directly, unless you really need to.
Use "sound cover" as much as possible. A squirrel moving, some wind in the branches, whatever. Move when you hear another noise, in order to cover your own noise.
Might look silly, but make sure not to eat too much or have any gas stuck in your guts. That makes a lot of noise sometimes... Make sure your nose is clean too (breathing should be as silent as possible as well). Breathing through your mouth will always make less noise than through your nose anyways.
Bend your knees a lot, and control your balance at all times. Each step should be totally controlled, and you should never transfer your weight to a foot swiftly. Make it slooooww... Flow calmly from back to front foot, putting the side of your foot on the ground first, and then rolling it flat IF there is nothing noisy under it (mocs are useful for that, since they let you feel the terrain very well).
Don't bend over. Stay straight AMAP.
Make small steps. It's easier to keep your balance like that. Being off balance is almost always noisy.
Move as slow as possible. If it takes you an hour to go through 100 feet of bush, then so be it.
Don't kill that elk unless you need the meat.
David