[SAump]

Throw your hands up like your calling time. Make a loud and decisive call.
"Time, that's a balk," followed by short explanation and award of base(s).
Some prefer to point and yell, "That's a Balk," followed by a short {2-3 word} explanation, followed by "Time," and award of base(s).

Short explanations: Start and stop, indirect step, dropped the ball, removed hand, no throw, etc.
{please add to list or improve above descriptions}

Don't coach pitcher during a game and don't begin discussion with coach.
If coach request explanation, repeat short 2-3 word description for pitcher and coach.
If coach continues onto field, prepare to dump him for PPP delay of game and arguing a proper judgment call with official.
Warm up coach with "What do you need coach?" and listen to coach.
Repeat short explantion and keep your mouth shut.
Let coach decide and do whatever he needs to do.
Good luck.