What's the proper way to mark the position of your ball?
The answer to this question can be found in the text of Rule 20 of the Rules of Golf Book and specifically in section one of that Rule. Rule 20-1 gives us guidance in that the position of a ball that is required to be replaced must be marked before it is lifted. If not required to be replaced, no need to mark its position (i.e. - dropping from casual water or a cart path).
The question of how is it to be marked is the real question. The Note at the end of the Rule gives us a “best practice” on how to accomplish this rather mundane feat. The text reads “The position of a ball to be lifted should be marked by placing a ball-marker, a small coin or other similar object immediately behind the ball.”
The coin or ball marker need not be placed immediately behind the ball as recommended. It may be placed to the side or even in front of the ball as long as it accurately marks the position of the ball. Just remember, when you replace the ball, put it back in front of, to the side of, or behind the ball marker depending on how you originally marked it.
Decision 20-1/16 goes on to give some additional examples of marking the position of the ball that are still legal but are not recommended. Those include placing the toe of a club at the side of a ball, using a tee to mark the ball or even scratching a line on the putting green (extremely discouraged).
Methods also may include using your foot, a poker chip, a small amount of powder, a lucky coin and even a coin with the last two digits of its mint year as your target score for the day!
On occasion, your ball marker may interfere with another player’s line of putt or stance and you’ll be asked to move your marker out of the way. What should you do?
Generally, line up your marker with a fixed object in the distance such as a tree or sign at a right angle to the player’s line of putt. Then place the head of your putter down on the ground to the side of your marker and move the coin over one or, if needed, two putter head lengths to the side. I always mark my ball with a coin “heads” side up. I flip the coin over to “tails” when asked to move my coin to the side. That way I know to move my marker back when I look down and see the marker as “tails” up instead of “heads”.
Remember, use the index or the table of contents to find the correct Rule that applies to the situation and follow the Rules of Golf to help yourself to enjoy the game of golf.