Plain Good Sportmanship/Sportswomanship
Don't drop or rattle your darts.
talk to him/her, tell him/her their score or the number he/she
needs. If he/she wants help, they can step off the line and ask
encouragement and gamesmanship to before he/she steps to the
line and after his/her turn is over.
short, do nothing to break a player's concentration while he is on the
This applies to opponents and teammates alike.
fun and a good time, but remember your manners too!