As I have said many times before, “Decoying is a definite love/hate relationship.” There is a very minute window that decoying is effective IMO (10-20 days). The timing and location has to be just right. If those two things come together, decoying is unbelievably an effective tool and the funnest thing to witness. Use it not at the right time or location be ready for heart break.
To fool a buck full of testosterone is not all that hard. The thing that will wreck it for you more times then not is the doe. I have had a doe over 100 yards away be upwind of my decoy and still blow clear the whole field numerous times. Or be uneasy enough where the shooter just off the field wanted to come out onto the field, but observed the does body language and turned the other direction. 
Food/Field edges can be great places to decoy, but be ready to have the field cleared by does also. 
Transitions (bottle necks) or staging areas are also great places as the does tend to just pass by and not observe pay attention the decoy as much.
If you can add some realism to your set up by movement of the head or tail this increases your chances to fool the does and increases your chances on the mature buck when he arrives. Primos Scarface, Flambeau Masters, Carry Lite or the Buck Wing Bobb’n Head decoys are the most popular real life looking decoys. The Primos and Buck Wing are both wind activated motion decoys.
I like to set up my buck decoys upwind 30 yards and quartering to me. I like for him to be in the open where he can be seen from some distance. The mature bucks will circle down wind of the decoy which puts them 30 yards or closer to me and they usually circle to the head which gives me a broad side shot of some kind. If I’m decoying I’m usually real aggressive with Horns and Grunts to attract attention. Also make sure you spray down the decoy with scent killing spray and wear latex gloves when handling. I usually put dominate buck urine on the ground or nearby branch to entice the mature ones to commit those last few crucial steps into the open for a shot.
I do not decoy much with does. However have had some success with doe decoys during the peak of the Rut and have caught a few 2.5 and 3.5 year olds searching when the bigger ones have been locked down with some does.
Like I said prepare yourself for some heart ache, but when it works, it sure is cool to see. Even if he is not a shooter that comes in. About my favorite thing in the world to see is a buck posture up and do that angled sideways walk into the decoy, no matter what the age of the buck is. There is nothing that gets the blood flowing more then seeing that. 
Good luck! 
