All I can tell you is crow hunting is like drugs. If you don't want to get hooked, don't even start! I'll give you a few tidbits I have learned in over then years of hunting the black bandit. First tip, go to www.crowbusters.com if you have not and look around.
Camo is king, but concealment and movement are right up there. Crows have eyes like hawks and will bust you out in a second if you are wiggling around.
I've let the first crow go and shot the first crow. I've found if you have a good setup and stay still the first crow will wing through and bring back his buddies. If you shoot at and miss the first crow you have ruined your set.
Setup can be friendly or fighting. I've shot crows off of both but the fighting setup is more entertaining. I prefer the crow/owl fight. One owl decoy and a couple of crow decoys are all you need. Place the owl in a tree and put one crow decoy on the ground as if the owl has killed it. Place one or more crow decoys in trees around the owl tree and then go into a fighting call sequence. When the crows see the owl and a possible dead buddy they will go nuts.
Again, do not move until you shoulder the gun for the first shot. If the crows are stirred up and in great numbers I swear they don't hear the gun or see you for a while.
Best of luck to you.