I wouldnt exactly call myself a "knowledgeable hunter". This was actually my first season hunting turkey. But by paying attention to what guys on this site were saying and reading magazine articles and watching a few instructional dvds on calling, I did manage to bag a nice bird last week.
So that being said here is my 2 cents..
Decoys; I use the same decoys you do, my only complaint with them is how bulky they are. If you stay put in one place for the whole sit they are very lifelike. But if you decide to move the smaller foam collapsible ones are so much more portable.
I made a few modifications to my tom decoy though. I used a fan from a tom I found dead on the road last year. I cut the middle feathers away from the rest of the fan so i could slide them up a couple inches and ziptie them back in place. making it look more like a jake. I bet you could do the same type of thing with the tail that comes with your decoys.
Calling; the most common advice I was getting about calls is to have several different types with you. I have a variety of different mouth calls, a slat call, a glass call and a call that has a slate on one side and a glass on the other. different slates and glass pot calls will produce different tones. as will different strikers. I also have a small box call, and a push pull call.
If you are in a spot that has turkeys, and they are seeking hens but dont respond to a call, try a different call. The bird I killed last week wouldnt respond to anything until I used that box call, then when he started to close the distance I used the glass/ slate call because I found out that it produces a low volume rich sounding yelp and cluck. the other slates are a little louder and I didnt want to spook him. Not saying to go out and drop a bunch of cash on every call you find, but if you pick them up here and there when they are on sale or at garage sales, you can put together a nice collection.
A good friend of mine told me that just like us, birds all have different voices. I think what he was trying to tell me is that no matter how good or bad your calling is, its still gonna sound like a turkey. the trick is to find the voice that the bird your hunting wants to hear.
Like these other guys have said I would definately try to get a little closer to where the birds are. If you know where they are roosting, and have some I dea where they head after flydown. set up as close as you can before day break and use soft calls.
here are the decays I was talking about.

