Spend more on calling tutorials than the call now. Most duck calls will call ducks if blown WELL, the most expensive is about useless if you can't make it work. Worry about getting a really good quack down and go from there. If nothing is flying I'll just blow some series of three to five spaced single quacks and maybe a lonesome hen thrown in and you'd be surprised how often I'll get and answer from down the bay. The other day I spent almost an hour conversing with a Susie down the bay before she picked up and came gliding into the decoys. I still use an old OLT Sonderman 66 and for retirement the guys at work went a bought me a couple Buck Gardner calls that seem to make a nice sound for me.
Practice and practice more. I used to drive truck and my calls would hang on the dash and tutorials in the Tape deck and later CD player and I'd practice going down the road, saves a lot of friction from the wife practicing in the truck rather than at home.