T-ball and Minors A (coach pitch) coaches should be referencing the guides below provided by Little League. Though they are specific to the younger kids, there may be material that is useful for older kids as well.
Little League Diamond Leader Training - The Little League Diamond Leader Program, a new initiative focused on educating volunteer coaches on their role supporting the social and emotional well-being of children.
Little League Rulebook App - The Rulebook app contains the Official Regulations, Playing Rules, and Operating Policies.
USA Baseball Mobile Coach - The USA Baseball Mobile Coach is a revolutionary tool that aims to simplify practice planning for baseball coaches at all levels.