0 How to serve

In order for your serving to be legal, you must make contact with the shuttle below your wrist and the racket shaft must point downward. Your entire racket head must be discernibly below any part of your racket hand before striking the shuttle. The underhand serve puts the shuttle in play at the beginning of each rally and, therefore, is probably the most important single stroke. The long serve is the basic singles serve. This serve directs the shuttle high and deep, and the shuttle should turn over and fall as close to the back boundary line as possible.

Long serve

The long serve resembles a forehand underhand swinging motion. Stand near the centerline and approximately 4 to 5 feet (1.2 to 1.5 m) behind the short service line. This positions you close to cetercourt and approximately equidistant from all of the corners. Your feet should be staggered up and back with your dominant foot back. the forefinger and thumb of your nondominant hand should hold the shuttle at its base, extended in front of your body about waist  level.

Short serve

Begin the short serve with the same preparation as the long serve. The primary exception is that you should stand much closer to the short service line, perhaps within 6 inches (15 cm) or less. Your racket arm begins in a similar backswing position, with your hand and wrist in a cocked position. As you release the shuttle, transfer your weight from your back foot to your forward foot and pull your arm down to contact the shuttle below waist height. However, as your racket hand comes forward, there is little or no wrist action because the shuttle is guided or pushed over the net rather than hit. The follow-through is short with your racket finishing up and in line with the serve.

Source:

Grice, Tony. 2008. Badminton: Steps to Success. Human Kinetics Inc.: USA.