I would personally go about finding a turkey call the same as a duck call. If you can find a hunting expo, or even on some call makers websites, just listen to the different sounds for different calls. Box, slate, tube, and diaphram calls all have different sounds and different advantages / disadvantages. If you are just starting maybe try a box or slate call to get used to making clucks, purrs, and yelps. Diaphram and tube calls are more technique sensative, for most, and will require more practice time.
Keep in mind that turkeys are all different and will respond more favorably to a certain type of call on any given day. They might not gobble at anything but a raspy box call one day, and another they might only respond to a low pitched diaphram. It's always good to keep a number of different calls in your vest while hunting.
That being said there are many different manufactures, but my personal favorite call is the Quaker Boy World Champion. I have killed more turkeys with this little diaphram call than any other. I also have a few custom made slate and box calls that I really like when the diaphram just is not cutting it.
As far as decoys, personally, I don't think they are needed for turkey hunting. I have killed far more turkeys not using decoys. Again, decoys are another piece of the aresenal in my vest that is always available. Featherlight decoys are ok. The best bet is to shop around for ones that you like--every year there are more and more decoys to choose from.
I had the best luck listening to hunting videos, hearing wild turkeys, and then practicing with the box and slate calls. When I was comfortable with those I added the diaphram with lots of practice.
I hope I have not beaten a dead horse, but I hope this is of some help.
Hunting in the bluegrass