Here are some basic guidelines to keep in mind when setting up on any gobbling bird:
Think ahead - If you are walking around and stopping to call occasionally, trying to get a gobbler to respond, try to stop in a spot that has a handy place to set up since many times the bird will be close and you need to get ready immediately.
Look for obstacles - When you get a bird to respond, quickly determine where the gobbler is located and what lies between you and the bird. If the gobbler has to hop a fence, climb down a hill, bust through some brush and cross a creek to get to you , odds are he's not going to go to that much trouble. This is not to say it's impossible, but you may as well increase your odds of success by moving and giving the gobbler a clearer path to your calling location.
When possible, try and get on the same elevation as the bird or above him. They will come downhill to your calling but they are much more comfortable coming to a location that is at the same level they are or higher. Turkey experts seem to think this has something to do with their basic survival instincts since it is much easier for them to spring into the air and avoid a predator when they are walking uphill. Or it could be they are like me and walking downhill hurts their knees and ankles more. Who knows.
Try to set up against a tree that is wider than your back - This will break up your outline better and also has the safety advantage of protecting your back if someone should sneak in behind you and accidentally send a shot in your direction. Many times, finding a big enough tree is not possible due to the fact there may not be any trees that big in the terrain you are hunting. Wide stumps, rocks and bushes or brush can be used if the terrain doesn't have any large trees. My last resort is setting up against a small tree in the open but I have done this and been successful. Another option when there really is nothing except some grass and weeds (Those of you who hunt Rio's or Merriam's especially) is to go prone. Laying prone is often very successful because when you think about where a turkey is looking from, his eyes are only 3 to 4 feet high and he can't really see that well into that grass patch up ahead of him.
Remove all sticks and leaves from your sitting area - This not only makes you more comfortable but it also eliminates much of the noise you make while sitting there. I do like to keep some leaves to scratch by my side if I can since this can often bring in a tom when nothing else will.
Minimize the chances for the gobbler to see you. I try and do several things to maximize my chances when a bird is coming in. First, if possible, I'll set up in an area where I won't be able to see the bird until he is in range. Conversely, the gobbler won't be able to see me either. When I set up on a ridge top and I'm calling a bird below me, I'll try and sit back from the rim far enough that I won't see the bird until he is in range. I'll also take advantage of any low brush around the tree I'm sitting against to break up my outline and sometimes I will move or cut some nearby brush or low branches for extra cover. The low brush or a low-profile blind will hide all of your hand movements when you're using a slate or box call. Another thing I like to do when I'm using decoys is to set the decoy off to the side of the direction I think the bird is coming from so when he gets close and he's staring that decoy down, I'm not sitting directly in his line of sight. This is a hunting tactic which is often used while duck hunting also.
Sit down and get comfortable - Many times you will have to wait an hour or more for a gobbler to come in all of the way. Try and get as comfortable as possible and lay out the various calls you are going to use so you can quickly get yours hands on any of them. This is also a good time to get out the sand paper or Scotch- Brite type scouring pad and condition any friction calls that you will be using.
Point your left shoulder (if right-handed) in the direction you think the gobbler will approach from - This will give you the maximum possible range of motion in case the gobbler circles and comes in from the side or another bird comes in from behind you. At best you can cover about 180 degrees. There are times when you still can't turn your body enough to get a shot. That is when you may have to try a left-handed shot (if you're right-handed). This is something most people never practice but it never hurts to practice moving your shotgun to your opposite shoulder and shooting with your opposite eye. You can be just as effective off both shoulders if you practice a little and if you hunt turkeys long enough, you'll be glad you did some day.
Get your gun ready - At this point, you are seated and ready to begin calling the bird in all of the way. This is a good time to check your gun to make sure it is loaded and ready. Some hunters do not even load their gun until they are set up which is ultimately the safest way of hunting. I used to be one of these until I clicked on an empty chamber one day while a huge gobbler stood there looking. I now carry a loaded gun once I leave my vehicle and it stays that way until I stop hunting for the day. I am pretty paranoid about checking the safety often while I'm moving around and as long as you are careful and use good common sense, I don't see any reason to not keep your gun loaded all of the time.
If you plan on using slate or box calls in your calling, place the gun in your lap with the muzzle pointed in the general direction of the gobbler. Hunters who use the mouth call exclusively have the advantage of being able to get their knee up and their shotgun raised and pointed in the general direction of the gobbling turkey well before it is in range.
Start calling - If you are like me and like using a lot of slate and friction calls, you cannot always keep your gun up and across one knee when you are calling a bird in. That's OK. Just start calling anyway and when the bird does get in view, you can wait until he crosses behind a tree or some other object and then raise your gun. If all else fails, you can slowly raise your gun on a gobbler in the open. He will sometimes see you and spook but it's worth a try anyway.
Shoot and celebrate - If everything else goes according to plans, you now have a gobbler in front of you within range. All you have to do is put your sights on his neck and pull the trigger!