I carry a FoxPro Firestorm or Fury 2 e-call, Primos Mojo Critter, a spare mag, a fishing scale, boresnake, pocket knife, sharpie marker, and some zip ties in my Cabela's call bag. I put the e-caller in first then the mojo on top of that and close the flap. The rest of the stuff are in the pockets on the bag.
I have a two point sling on my rifle that I put on first with the sling across my chest and the rifle, muzzle up, across my back, with the top of the sling on my left shoulder, across my chest, and the bottom of the sling around my right hip. Then I put the bag through the other shoulder across my chest/back, with the bag sitting about my left hip.
I use Primos Rapid Pivot bipod, so I put the legs through the bag, under the flap, with the strap in between the legs, and then snap it close to secure it.
I also use a Primos Double Bull chair on 99% of my sets. I fold it up, and put it on top of the call bag diagonally kinda.
So basically I'm carrying a lot of crap but have both hands mostly free while walking in. The chair is the most cumbersome part, but I love sitting up above the grass for visibility.
When I get to a spot to call, I drop my chair and remove my shooting sticks, walk out to where I want to set the call. Undo the top flap, set out the mojo and the e-call. If the grass is tall and there's not anywhere to get the call up off the ground, I'll set my bag down and put the e-call on top of it. The sounds carries much better when the call is off the ground. I would carry a tripod for the call but I really don't have anymore room for anything else and the bag works fine.
Then I go back to my chair/sticks, unsling the rifle, get set, and start calling. I also have a paracord drag I had a friend make to drag the dead coyotes back to the truck. It has six loops so I can drag a few coyotes if I have to, I've drug three back and that pretty much sucks, but the adrenaline from the kills helped, haha.
Sorry if this was too long.
This is the bag I use
http://www.cabelas.com/product/Cabelas-Pro-E-Call-Case/1429040.uts