If you opt to go the decoy and call route, I would encourage you to pick-up some carry-lite full body decoys to augment your crane spread. Kristan's adivce on calling is pretty spot-on. We use a mix of commercial crane calls, which sound more like a kazoo than a sandhill crane. I made 135 hand painted crane silhouettes over our first three years of hunting cranes. We use the full body decoys deployed as about a quarter of your spread with mud-washed fully camouflaged Final Approach layout blinds interpersed. I modified some Tim Grounds cocobola long magnum honker calls via reed manipulation, to funcion as crane calls. They are deadly accurate in reproducing the "woody" knock/yodel of a sandhill crane. I have tried the silo-sock decoys in NoDak hunts with mixed success. Wind speed averages 13 mph on the Missourri Cateaou area of NoDak. Flapping silo-socks are a deal breaker in high/moderate winds to get cranes in. I also eventually painted the interior fabric with auto primer grey to get rid of the white "hole" that flairs birds working the spread in the upwind quadrant.
As others have mentioned a spread of cranes with a seperate spread of geese has worked best for us. I routinely see intermixed species flocks on the ground, but the birds don't decoy as well to a spread set-up that way.
If they are giving you the long yodel as they approach or fly-by, hit them with the same call. When they turn and break your way, if they continue to emit the long yodel, just match each call with a similar response each time you hear them call, i.e. don't over call them like excited geese on the ground. If is nothing to have a flock set-up at 100 yards out and start to coast your way with their wings locked and then drift off to the side at the edge of range and circle again. Like geese when they are quartering directly away from you, hit them with frequent long yodels or the dispute yodel call. Inquisitive and cautious birds, particularly in small family group flocks will break into the short knock call that Kristan mentions, this is just a truncated yodel, but it signals to you they are looking hard, frequently picking-up movement in the spread or something that looks amiss. When this happens, just give them that same short call in response each time. There is another call that essentially is the long yodel done in sequence which sounds a bit like the spit-note comeback call. I call this the dispute call. This occurs usually when two cranes or more engage in a food or feeding spot dispute. It works well on distant birds to pull them off their flight line. It is not an easy call to mimic. If you can make it, it is another call to hit a flock that has broken-off to circle again and set-up to come in.
If you can get a small flock, with multiple birds in the air working your spread at varying distances out, to commit and land, you will be rewarded, even if they jump prior other birds coming in. A flock landing is the visual trigger for these birds to readily commit to decoys.
Juveniles emit a nasal drawn-out peep, which you can easily imitate on a standard Roy Gonia dog whistle. In fog or poor visibility conditions, this call works well. Cranes will sit-out most foggy mornings, waiting for the sun to burn it off. If birds are moving, family groups respond well to the juvenile "peep". I've succeeded in pushing birds off the decoy spread routinely with their feet down and dropping, when I have used this call in good visibility conditions...why I mention it last! It is not a finishing call!
We hunt in hilly rolling terrain, preferring to set-up in harvested wheat fields at least a mile out from a roost. Avoid setting-up in line of sight with their roosts. We like to set on the highest point in the field where birds are feeding. We keep our ground blinds below the hill's crest and try to site them in the sun shadows of the terrain, if the wind direction is cooperative. Face masks and no shiny eyeglasses/jewelry without a hat brim over them is the requirement. IF you have permission and don't have a ground blind, you can set-up by digging a shallow foxhole about knee deep to enable you to lower your silhouette. Brush yourself in well to match local vegetation. In a pinch I have used ditches and hale bales for blinds. We usually drop the decoys and blinds and then designate our younger hunting party members to drive the trucks well away from the spread site, easily 3/4 of a mile.
Birds are usually off the roost and out feeding by 11:00AM. In NoDak, hunting for cranes ceases at 1;00PM and there is no shooting allowed over water. If you have not limited, sit tight. The birds will lift-off in smaller flocks down to family groups and start drifting around. We call this the "Looky Lou" flight, as birds move around to socialize and interact. These birds are looking for company, as well as lost mates for single birds moving around; they are very willing to decoy. Fewer eyes on you, as several have said, equates to a better probability of success, so don't pull your spread too early.
Lessers are normally what you will encounter, some migrants originate from northeast Russia in the western Canadian provinces and Alaska. NoDak Fish and Game "slides" their season around each year or two to try and allow the vast majority of the smaller population size greater sandhills through the State prior opening the season. Greaters are huge birds, a true trophy. They all eat well...very hard to wreck crane meat. You can brine the legs and thighs to tenderize them, prior grilling, smoking, etc. Great soup and sausage birds from all meat scraps. It was nice to read that somebody else pulls all the meat they can find off their bagged cranes.
As several others have said, cripples can be quite dangerous birds. we use the same touch them with the muzzle of a loaded gun technique you would on bears. The only time I have used a dog to retrieve a crane was a dead bird on solid ice. We still fired a load of #2s into its head/neck prior sending the dog.
Heavy Shot B, #2, or Federal steel BBB are preferred loads. Heavy shot #2 on decoying birds will give you clean consistent kills with low crippling losses. They can take a lot of shot and still fly. If you do not break a wing or deliver a fatal shot charge, they will coast a long way prior impact. This makes for some very long walks and an hour or more of looking, since you can't take advantage of a dog's nose. We usually make a point of driving and glassing the section around where we hunt for cripples, if we are done early.