Keeping the wind in your face chaps and working out your approach to suit will also help..........its also pretty handy to try and put yourself between them and the wood they want to be in. 
  
Now, this may open a can of worms, but in my humble opinion it dont take any magical skill to get within a 100yds of Roe, Fallow or even Muntjac......cant say for Reds or Sika as I have never stalked them although on open moorland it would obviously be a lot more difficult. 
  
Bottom line is, getting to know a creatures habits will beat the arse of all the washing in this and dont sweat in that any day