You’ll notice the word “eliminate” instead of “replace.” Often, it’s difficult or impossible to replace “was” with another verb. But it’s often possible to eliminate it altogether by turning the sentence around so the stronger verb following “was” becomes the primary verb.
Example: His eyes were shaded by a tan Stetson.
Stronger: A tan Stetson shaded his face.
Example: The pathway was lined with fragrant petunias.
Stronger: Fragrant petunias lined the pathway.
Not all sentences can be turned around this way. If the sentence rebels, leave the passive verb. Most sentences, though, brighten and get stronger when the passive verbs are eliminated.