There are two types of plies in ballet: the demi-plie and the grand plie. In both cases, you stand in first position with your legs at a 180-degree angle, keeping your back and shoulders straight and your heels on the floor. In a demi-plie, keeping your body straight, bend your knees to about a half bend for two counts, then straighten your legs for two counts. In a grand plie, bend your knees a bit deeper, until your thighs are horizontal, forming a diamond shape. Go down to a count of four and back up to a count of four. Your heels will lift during the full bend, and will return to the floor when you return to a standing position. If you're doing a grand plie from the second position, however, your heels will remain on the floor throughout the entire exercise.
As with most ballet moves, the only way you can perform better plies is by practicing. A professional ballet dancer will practice for hours each day to perfect particular dance moves. The plie is a key element of ballet dancing, and you'll need significant practice to hone and perfect this move. The best way to do this is to practice in front of a mirror. When practicing in a ballet studio, stand facing the barre and concentrate on your movement as you perform the plie. Particular areas of focus include your posture and attaining the proper degree of knee bend while performing the move as gracefully as possible.
The key to a properly performed plie is alignment. When practicing plies, it can be helpful to imagine a plumb line running down the center of your body, and move up and down along that line. During the descent, you should release your hip joints to widen your pelvis on the way down. When ascending, keep your weight equally balanced on both feet and so that the body moves up from the strength of your legs. Visualizing yourself performing a proper plie may also help you perform better. In a 2008 article in "Dance Magazine," Eric Franklin, founder of the Institute for Movement Imagery Education, suggests that you think of a magic carpet lifting your pelvis up and down. This image, claims Franklin, will prevent you from allowing your legs to do all the work.
In the same "Dance Magazine" article, Juilliard ballet teacher Risa Steinberg tells students to focus on moving "flesh away from the groin," which causes dancers to open their legs wider. This, says Steinberg, causes the plie to gracefully "float out," so it's not as if the dancer is simply moving up and down. Steinberg also looks at the plie philosophically, noting that this move is "an action, not a position." She see the plie as ballet's "connective tissue," fulfilling a role in dance similar to that of the word "and" in the English language, and she describes the plie as a transitional movement that will take you from "one thought to another."
Another factor to consider in improving your plies is your shoes and how well they fit. If your shoes are too tight, this may prevent your foot from fully spreading out.