There are no short cuts when learning to use air operated calls. You will need to practice a lot , unless you are naturally gifted.. One thing for sure, Trumpet calls are an effective weapon in a person's hunting arsenal..
Get a good quality call, put it in your vehicle or by your chair at home and practice for a few minutes a day - year round. It will take some confidence in your ability to hunt with one, but turkeys are forgiving of a bad note or two. Just keep pluggin along.
There have been some great callmakers mentioned already, so I won't add to the list. The search function here is an asset.. Good luck. I have called in a fairly high stack of Gobblers with a trumpet that didn't respond to anything else.