I always hunt on the ground...
One thing I have learned is that you never want to be set up where the deer are likely to be looking. If they are following a trail and moving then you want to be off to the side. You want to be as still as possible and 'become' the background. In my experience the bucks are easier to hide from as they are usually alone and traveling with a mission in mind. Unless they smell or see you they will keep moving. Does are almost always in groups and usually there is one doe that is smart enough to know that you don't belong there - even if she doesn't smell you or see you move. They just 'know'.
I've only hunted for three years but I spend time in the woods photographing the deer all year long. Early in the season they are not spooked as easy - once the rifle season starts they spook at anything... As stated by others - keep your scent in control and stay upwind.
GOOD LUCK!