Let me try this, I hope I can help you guys out. If I leav something out or if you have any questions fire away.
First hold the call in the webbing between your thumb and pointer finger (this will be your on hand). Don't completely close it over the end of the call, but leave a "hole" about the size of a quarter. I usually raise up my middle finger a touch, and you can play with how much, as it will change the tone of the call.
Put your other hand (off hand) with the tips of your off hand touching the knuckles of your on hand. How much you cover your on hand causes the pitch to change. Covering it more fully causes a lower tone, taking it away a bit causes it to go higher.
Put your tounge behind your bottom teeth, where it ramps down. For greeting calls, you can try saying to-whit or whatever fits your style. You must force the air through quickly to break the reed over and cause it to crack. Honks are basically the end "whit, etc", forcing the air through the same. For a laydown call, keep the call covered pretty well, and I say something close to doo, doo.
I may not have described this well, but it's pretty late and I may not be thinking quite straight. If this doesn't help you Shawn Stahl's Honker Talk or Fred Zink's Art of Paralyzing Geese are two great videos that go very in-depth and they can probably describe it better than I. Don't give up on those short reeds, they are hard to master (and I haven't come close to this) but well worth trying to learn.
Questions, comments? I'll try to check in and try to help or to clarify anything. If I think of a better way to describe something, I'll post up. I am going to grab a call tomorrow and make sure what I say matches with what I posted. It's kind of hard, I don't really say anything, but am trying to come close to what I blow.
Also one thing that can help is adding "voice" when you call, or grunting into it. It will help get a better sound, and really works.