I started my kids with an old Buck Gardner freebie CD we got with a cheap poly call years before I started building calls. You're not going to set the world on fire with it, but it gives you some good starting points that let a guy build a solid foundation for calling.
I have both the Carlson and RnT sets and both are excellent. I think the Buck Gardner cd is availible track by track for free from thier website as well.
Bob