Hunter's Specialties offers several different types of diaphram calls and even have some that have instructional audio tapes that are included. Regardless, the diaphram is probably the hardest to use. If you can't seem to get the hang of it I would recommend getting a slate call.
Also, has anyone checked out that new Super Black Eagle with the Steady Grip. A friend of mine got one and loves it. He says he's even going to use it for waterfowl this season.