Balks and hit by batted ball...

[PatF]

Invest a few bucks in a very good video from Jim Evans. It demonstrates a whole lot of the do's and don'ts and what is and what is not allowed regarding pitching and balks enforcement.

I purchased a copy to use for our local umpire training this year. Very good information. Much better than "See A Balk, Call a Balk", which I purchased a couple of years ago.
Here's the link for Jim Evans.
http://www.umpireacademy.com/tapes.html