The fastest way to make a close end confusing is to pick up bowls before both sides agree. A short shared routine keeps evidence in place.
Freeze the head
World Bowls law 22.2 says no bowl is moved until opponents agree whether it is a shot, apart from a bowl that must be moved to allow another measurement. Keep feet, cloths and phones away from the jack and the bowls under discussion.
Agree the easy shots first
Identify bowls clearly nearer than the nearest opposing bowl. As shots are agreed, law 22 allows those bowls to be removed and grouped clear of measuring. Both sides must agree the number in the group.
Measure only the unresolved pair
Measure between the nearest points of bowl and jack. Choose a suitable tool and steady any bowl likely to fall as the law permits. If the measure itself moves a bowl or jack, stop and follow the displacement procedure rather than guessing.
Call for a neutral decision
If the opponents still disagree, ask the marker or umpire under the event procedure. Once the shot count is settled, communicate the same number to the scorekeeper and check the running total before the next end.
Source: World Bowls Laws of the Sport, laws 22–23. Check your national regulations and event conditions before a competitive game.
A score can be corrected; a disturbed head is much harder to reconstruct.
For a shared view of close heads, try WGTS for iPhone or WGTS for Android. Use the official measuring procedure whenever your competition requires it.