Even the Logo man for the Australian Open keeps his arm up!
Serving up another tip! Notice the pro’s service motion. The arm lifts up and his/her armpit is visible. This allows for a higher lift and the hand opens on the release. Think 3 T’s – toss, tuck, turn. The left arm tucks toward the chest/belly button and the hips and shoulders turn. Keep your head/face up and behind the racquet. Notice that the logo man for the Australian Open is even doing it correctly!