The only time I've offered advice is during "friendlies" tournaments. Usually these are tryouts for the travel teams. Rules are relaxed, everyone bats, etc.
I've told a coach about pitching violations once they removed that particular girl from the pitching position. I have also offered some inputs to coaches regarding their catchers - particularly those who have a tendency to stand up when catching a pitch, thus blocking the umpire's view.
Would never advise anyone during competitive play. Take the outs!
