Learn. Try. Practice.
All of the following GIFs were taken from this video of *NSYNC performing "This I Promise You" at MTV's "Snowed In" circa 2000.
Each of the following techniques are tried and tested.
The Gum Sway
How you do it: Sway back and forth to the beat of the song. Chew your gum with each sway. Wear burettes.
The Ugly Cry
How you do it: Cry. Chew your gum. Cry.
The Water Bottle Wave
How you do it: Hold your water bottle in the air. Do the wave. Stay hydrated.