To understand how to blow a duck call, today's market also offers a variety of instructional video tapes. Some that I have seen were made by Buck Gardner and Eli Haydel. I believe anyone, with proper instruction, can learn the basic five notes of a mallard hen in less than one hour, and be able to call and decoy ducks. Let's start with a basic, moderately-priced call. These are both acrylic calls with double reeds, and always sound good right out of the package.
Most beginners try to blow too hard.
Simply take the call in the fork of your hand, between the thumb and forefinger. Cover the mouthpiece of the call with your lips, letting no air escape around the outside edge of the call. Practice over and over this single note until it sounds like a mallard hen. No use attempting to quack more notes until you can do one note with confidence. Everyone is familiar with this tune.