I know this is basic advice, and has been mentioned many times before, but i cannot stress the importance of not making sudden movements when stalking.
It doesn't make a jot of difference if you have the latest all singing all dancing cammo, you will be seen.
In the states we referred to other hunters we observed in the field as 'pumpkin coats' because of the blaze orange, but when we stalked a deer on the plains it wasn't the bright colours that brought us to the attention of the deer it was movement, they could see us 3 miles away i kid you not.
The reason i am writing this is my experince this afternoon, i finally found where the red deer have been feeding (the most inaccessable place you could imagine, not even a quad can get there safely) it was a strong easterly wind but fitted in with my plans, i came across a gate which i had to climb, before i did i spied across the valley and observed 6 red hinds, they were settled except the lead hind, she just wouldn't settle down, so i figured that i wouldn't be skylined if i got over the gate but the background was a grass field, so i very, very slowly placed my sticks over the gate and stepped up, using the bino's the hind was looking but not right at me, i stepped over and kicked my sticks, i made a grab for them and the sudden movement caught her eye, i froze but she wasn't stupid, off she trotted with the 5 others following, i ranged it out of curiosity, over 600 yards away.
It wasn't the first time and won't be last but very frustrating all the same.