Stand still and watch the shot. If you can't render this simple courtesy, then you do not belong on a golf course. Clearly state your score when holed out. Making other players ask what you had on the hole is a breach of etiquette. Check the card occasionally to insure accuracy.
Golf is all about accurate scoring.
After the game is over the appropriate handicap adjustments can and should be made. Incidental to this rule is the requirement for each golfer to have a standard USGA handicap. Without an official handicap, you are not able to truly compete in golf, and in every match you play you have brought an element of unfairness to the game. Accurate handicaps provide the only fair basis for competition. Playing without a handicap is a breach of etiquette, especially in light of how easy and inexpensive it is to officially obtain one.