We are required by our association to do the clock several times a year at varsity level games. It has taught me several things to be aware off and to do while on court.
First, and simplest, is that if you can not see the timekeeper he can not see you. Make sure you have eye contact with the timer before you give the ball off to the inbounder.
Chirps are fine for birds
but not fine in a gym full of screaming fans. Blow that Fox 40 with force and length.
Last minute of a close game make sure you start a count when the ball is touched inbounds and make the hand arm motion very visible. Under no circumstances allow a home clock not to start after 3 counts. If the advantage is to the home team by not starting the clock, home has the ball, stop the play. Walk over to the table and have the clock reset. If home coach says anything simply say to him/her, The clock was not started and I have corrected it. Walk away and restart or have a partner restart the game.
Dont hesitate to take the timer to task or even replace him. A few weeks back I had to tell a timer that he could either talk on the cell phone or do the clock. If he was going to do the clock he had to put the phone out of sight.