Personally, I always like a jake decoy with at least one hen. I believe it can increase the likelihood of a tom coming in, as he will generally approach the jake when he does come in. Keep in mind that a male decoy can intimidate a non-dominant tom, but an alert jake decoy would be the least likely to intimidate. I often use a strutting jake, as I more often have a tom approach, than shy away. I usually hunt fields that I know the turkeys are using, and I place a ground blind out in the field, where the turkeys tend to be. I don't worry about turkeys being intimidated by the blind in the middle of the field. One pasture I hunt has a spot in it where turkeys like to dust, and I will set my blind there. My blind doesn't flap in a breeze; if it did I would have concerns about turkeys shying from it. I set the jake at a distance I am comfortable shooting at, as I anticipate the tom going to the jake (25 yds, usually if gun hunting, but I've set a jake up as close as 6 yds when bowhunting). I've also set a blind up very close to the roost area (the afternoon before the hunt), in a circumstance in which the birds were roosting on property I hunt, but traveling off the property, from the roost.
I may owl call before flydown time and after setting up in the dark of early morning, just to confirm where birds are roosted, but I generally like to wait to see if they gobble without my intervention. As long as I know birds are consistently using a field, I'm not to worried about where they roost. Keep in mind, too, you may have birds roosted very near that for whatever reason aren't gobbling on a particular morning. Also, pre-season scouting is incredibly valuable, as well as knowing the property you are hunting.

As far as using a ground blind in the woods, I have done that, but generally when hunting near a roost, first thing. I don't like carrying a blind with me during the day through the woods, and generally won't bring decoys, either. In that situation, if i have a bird answer me, I will choose to set up so there is a rise in the topography within 40 yds of the tree I sit against, so the turkey won't expect to see a hen until he is on that rise, and then he will be close enough for me to shoot. (if he comes in from where I expect him to.
Hey, this is my advice, based on my experience; others may have different opinions on the best way. Good luck and have fun!