a box call is the #1 USED call in the woods hands down due to its ease of use and you can make all 4 main turkey vocalizations on it as well as a gobble. Having said that i dont even own one and chances are i never will have one in my pack, i just personally dont like them. TO ME they are bulky and noisy to carry, however they are very loud which can be useful on windy days.
I would start with a slate or a decent glass over glass style call, those seem to be the easiest to be consistent on. Dont rule our a good aluminum call (ala Lights Out Aluminum which is an AWESOME call)
with practice any can be easy to use, the key is to be consistent in using them to where you can yelp, cut, cluck and purr with no screeches or slipping. in addition be sure to practice useing them in non traditional positions because you will have TONS of those while in the woods. learn to use them in a variety of sitting positions as well as with gloves on (if you wear them normally) and with a gun on your knee. there is a big difference in being good at using them in a car or just sitting on the couch at your house then in actual hunting positions.
mouth calls will be tough to start with and took me a long time to be decent at them but some are quicker at learning then others so its never to early to start.
lastly always remember, you dont have to sound like a professional caller, you just have to be consistent at it. the more important factor is WHEN to call, HOW MUCH to call and HOW AGGRESSIVE to call. those all come with experience.