My favorite in a push pull is the Knight and Hale Lonesome Hen. They also have CD's of real turkey sounds for you to practice by.
I also like the pot and striker calls. They're easy to learn and you can adjust the volume easily as well.
Box calls are large, tend to make noise when you don't want them to, and can require a lot of movement, but they can work well for a beginner.
Whatever, you need to practice until the calls are second nature. When you're actually talking to a turkey, you can really forget stuff in teh excitement.
And just like fishing lures, it's easy to buy too many calls!
