Based on my own call making experience, I would recommend sticking with .004 or thinner materials (.003/.0025-proph, etc.) and start out making two or three reed calls based on the standard designs you see on the market.
If you are making calls for yourself, learn to go through a standard cut procedure, starting out with single cuts (long reed only) and working through the various cut types off of that. A standard progression of cuts would be a single angle cut, then a V-cut, a modified V (cutting ends off of tabs), then a combo cut (remove one side tab), bat cut (remove both side tabs),...or remove the center tab (on a V-cut) for a ghost cut.
If you are making calls for others, leave the reeds uncut and let them learn to go through the cut progression themselves.
Other general info:
Very small changes in the cuts in the sound reed can greatly affect the call sound. When making cuts, make small cuts first and deepen if needed to improve sound.
Don't cut the secondary reeds unless you just can't get the right sound after going through the cut progression, and if you do end up cutting the secondary reeds at all, make very fine nicks in the reeds (large cuts in the secondary reeds will almost always deaden a call)
The deeper the cuts you make in a call, the lower the tone and the raspier the call will sound, in general (varies to a degree based on the initial stretch you put in the reeds)
Shaving the long reed laterally (along the edge) can sometimes improve the sound when all else fails.
...Just a few thoughts....
