Two-Finger Method
Inflate a balloon, leaving about an inch or so at the end as a "tail." Wrap the balloon&'s tail around your index and middle fingers and push the end of the tail underneath the loop you&'ve made, through the crack between your fingers. Then simply pull the tail through to form a knot.
Big Loop Method
Inflate a balloon, again leaving an inch or so of slack as a "tail." Wrap the tail around your index and middle finger, holding it closed with your thumb. Insert the tail under your thumb and between your fingers, pulling it up so that it rests atop and between your fingers. Simply pull your fingers out of the big loop, and the knot is tied.
Fork Method
Holding the inflated balloon between your knees, wrap the balloon&'s "tail" around a fork (a two-pronged carving-style fork works best) and pull the tail through the loop between two of the fork tines. Pull the fork out of the wrapped tail to close the knot.
Balloon-Tying Tool
Specialized balloon-tying tools are available for purchase. They are designed to relieve pressure on your fingers and make tying even hundreds of balloons easy, without pain or discomfort.