Take time to observe
In brief
A screen is useful for capturing, but disappears if the intervening piece moves. Count the obstacles again before relying on a cannon attack.
Check the cannon’s screen
A screen is useful for capturing, but disappears if the intervening piece moves. Count the obstacles again before relying on a cannon attack.
Free your horses
A horse surrounded by its own pieces may have few ways out. Always check the first intersection along its move.
Watch the generals’ file
Moving a piece from between the two generals can open a forbidden file. A threat cannot be assessed by looking only at the piece that moved.