Chris has it pretty much spot on.
The biggest problem most people suffer from to start with is enthusiasum (SP?).
That is, they want to get out and see the deer so set off much too quickly making loads of noise and movement - only to be dissapointed.
Take your time, move slowly. Aim for one step every 40 - 60 seconds or so when not looking around ! It's really difficult to walk that slowly - it's against everything we've been brought up to value in this country (time is money etc!) but it's worth it. I don't expect you'll get that slow (in truth I rarely walk at that pace unless I'm know I'm close and then it can be much slower than that even !) but if you get half way there it'll help.
Deer will spot movement far outside of hearing distance. Just as we do. If someone across the valley stands still it can be quite difficult to spot them but if they move - even with full camo on - they can be spotted easliy.
Deer see the same thing. By walking slowly you can remove alot of the problem.
The idea is to see the deer before they see you, the best way you can do that is to use binos or a decent camera - some sort of optical device.
Don't worry about the camera making a noise, you'll have time to take a piccie with no problem at all. Often they wont move anyway with sort of noise. Your movement will scare them away much more.
Be aware of all the wildlife around you For instance, how other birds react to one birds alarm call.
I don't think deer react too much to other wildlife as there aren't any natural predators in the Uk apart from us but they do take a bit of notice and the game can be up before it's started !
Good luck and I look forward to seeing the results...
In a world whose only quarrel with instant gratification is that it takes too long, we are practitioners of a dying art: patience."