Clear and concise communication using proper hand signals and body language, together with a commanding voice, are necessary ingredients for successful officials.
Signaling at the spot. When you call a foul or violation, your body language sends a message to everyone watching. Raise your fisted (for a foul) or open (for a violation) hand high and straight above your head to stop the clock. A bent arm looks weak and shows people you're unsure of your call. Verbalizing what you've called while giving the proper signal at the spot is important.
Selling a call is like raising your voice. Sometimes it is necessary and effective. Do it too often and people get angry or turned off. Sell a call only when necessary. Obvious calls need good signals too, but close calls need a little extra emphasis to communicate to everyone clearly. Don't over-sell; you don't want to embarrass a player or appear that you're caught up in the emotion of the game.
Signaling to the scorer's table. Equally important is your presentation to the scorer's table. That's one of the few times where all eyes in the gym are focused on you.
Come to a complete stop about 10-15 feet from the scorer's table. (You don't want to get too close.) Make eye contact with the scorer. Slowly state the color of the shirt and the fouler's number. Signal the number (one digit at a time) with one hand as you say the words. Hold your hand at about chin height and off to the side of your face making it easy for the scorer to see.
Slow down and think about your signals as a language. If you "speak" slowly and clearly and use the right "words," the correct message and tone will get across.