I don't worry too much about it if the wind is right, and I try to stay out of blinds where wind will be incorrect, but sometimes it isn't possible. I picked up a couple of those earth scent pucks this year and use those, and they seem to allow for some good cover scent.
I always try to keep noise to a minimum as far as talking and stuff, but I have had experiences and I challenge you all to do the same, where I had kids in a blind with windows open (box type not open tripod or tree stand) and they were talking away and I couldn't hear them standing more than 10 feet away. I have had my chairs bang with deer present and they don't care, half the time I think they don't even hear it. Shoot, with the right wind I have a hard time hearing gun shots more than 400 yards away, and I am sure you all have had that same experience.
However, I do think movement is the biggest thing to keep quiet while in the blind. They can pick up a turning head and will become alert and easy to spook with the wrong kinds of movement. So I do try to keep that to a minimum.