After a couple of minutes of swishing and flipping your swatch, pull it out and gently press out some of the water. Spread it on a towel and give it a look.
This picture was taken about five minutes after I started. The swatch laid out flat in that time and was already beginning to get fuzzy. The height shrunk in this time to about 4.5 inches, while the width stayed about the same as the original swatch.
If you're not making good progress on getting your swatch to felt, shock it with a cold water rinse before returning it to the hot water. This seems to help the fibers come together a little more easily.
Remember that every yarn, even different colors of the same yarn, can felt differently and to have patience if your yarn isn't felting immediately.
