"Come on, act like you've scored before!"
In Disney's film D3: The Mighty Ducks, the high school team's coach, Ted Orion, yelled at his players for over-celebrating their first goal of the season.
Though the idea comes from a fictional movie aimed at a childish audience, this call for humility was an excellent piece of advice. If a player knows he can score, he does not have to show off. He knows he'll do it again.