Chuzhakin’s System. Rule No 2.
Read the concepts of the system at: http://www.chess.com/blog/Chuzhakin/chuzhakins-system
2. Objects under attack
Hazardous elements are objects under attack, i.e. in cases when the number of attacks on an object exceeds the number of defenses.
Priorities: crucial HE.
At first glance, everything is simple: if a piece is under attack, you should defend it or move it away. More complicated positions appear when an enemy piece is attacked in return.
from Chapter 7. Standard Methods of Using HEs
If each side has a crucial HE, for example HE No2 or checkmate threat, first of all you should consider getting rid from your HE with tempo. If we talk about a piece under attack, this can be defense of your piece or playing against the attacking object, or interference with the line of attack, or escape of your piece to a safe position.
Another type of playing when both sides have crucial HEs - pieces under attack - is desperado.
The same method is useful in many positions.