Final answer:
When planning to back up a vehicle, it's important to look in all four directions first, and then continue to look behind you while backing up.
Step-by-step explanation:
When planning to back up a vehicle, it is important to first look in all four directions: left, right, forward, and backward. This allows you to check for any potential obstacles or hazards that may be in your path. After looking in all four directions, you should continue to look behind you while backing up to ensure the area remains clear.