Avoid passive voice.

Revise sentences in which you do not explicitly state who is doing what to whom.

Passive voice = was, is, being, or has been + a verb in the past tense.

Passive voice: The ball was kicked.
You can't tell who "did" the kicking.

Active voice: John kicked the ball.
John "did" the "kicking." John is the grammatical subject of the sentence.