Personally, I think its a real shame when those new to predator hunting start off with electronic calls and don't learn how to use mouth calls first. A lot of the challenge, enjoyment and sense of accomplishment in pitting your skills against theirs is lost. And what do you do when you get out there and find the that electronic call won't work for some reason and you don't have or know how to use a mouth call? I've managed to call predators very successfully for over 5 decades using only mouth calls - most of them that I made myself, and I am not a believer in wearing camo either (its all about set up).
A closed (enclosed) reed mouth call is very easy to learn, and will often bring in predators with your first attempt at calling. There are some very good (and cheap) commercial distress calls that are a great choice to learn with, and they will produce predators. Eventually you'll want to get into open reed and howlers too as they add a bunch of versatility, new tricks to your bag and will extend your successful calling season. A good intermediary call between the closed and open reeds is a bite call, which is easier to learn than the open reeds and howlers. Eventually you may also want to get into using diaphragm calls, which are the hardest to learn (unless you've already learned how to use them for turkey, elk, etc). Kind of a progressive thing where you have to learn how to crawl before you can walk and eventually run. Skills learned in each step help you with the next one.
While all mouth call reeds are tunable to varying degrees, generally the wood barreled calls produce the best sounds in any predator call. Wood adds resonance to the sound much better than man made materials do. A good choice to start with is Dan Thompson's PC series, which are modeled after the old Weems calls. Cheap, reliable and they produce very life like sounds. Just pick the model that emanates the predominate prey species in your area. Even the old Weems calls can be still be found on places like Ebay, but at a higher collector price than Dan's.
Have fun.