Stalking deer with a bow is probably one of my #1 favorite passtimes.

I practice all summer, and apply it to hunting in the fall. I usually do spot-and-stalk, but I also do still-hunting (which is actually harder). After many failures, here are some important tricks I' ve learned:
1) Watch the wind. This one is obvious, but hard to do when you' re stalking a moving deer.
2) Always assume there' s a deer behind the next bush. Never let your guard down. So many times I' ve been stalking a few deer I spotted, couldn' t find them, started walking, and jumped them.
3) Be aware of your surroundings. My most common problem is letting myself sneak up on a deer without knowing it. Next thing I know, there' s a deer looking at me and a tail bobbing away. Make sure you look around every couple steps.
4) Keep it quiet. Do your best not to step on branches, pine cones, etc. Grass brushing you doesn' t seem to bother them near as much as sharp sounds like snapping branches.
5) Find the deer before they find you. Often, this involves sitting in a stand until you spot one. Sometimes, it' s just quietly still-hunting when you know there' s deer around. If a deer sees you first, the odds are it' s over.
6) If a deer spots you, don' t panic. Stand completely still. When the deer looks down, slowly get on the ground and do a belly crawl to the nearest tree.
These are just a few things I' ve learned. I' m still working on honing my skills, being that this is only my second year bowhunting.

Hope this helps!
-Spike Buck