I just got off the phone with one of the reviewers who is also an English teacher. She encouraged me to mention to everyone who is writing and/or editing a book right now several issues that we see over and over again in the submissions that we receive. I'll bring them here for discussion over the next several days.
First, many of our members overuse passive voice. Passive voice is when the verb acts on the subject of the sentence rather than the object. Example, "The vase was broken by the wind." or "The boy was beaten by his father."
Normally, you would use passive voice to vary the rhythm of your prose or to create an effect. It slows the read by refocusing the normal way the reader absorbs information. In colloquial terms, people use passive voice more when speaking than is appropriate when writing. Therefore, it works best in dialogue. However, when overused, it creates distance and introduces an awkward cadence to the story. Rather than being a tool to create interest, it overcomplicates your palette and makes reading onerous.
The percentage of passive sentences in a piece will depend on your style. I aim at 6 to 8% of my sentences in a long story. However, many authors come in around 10 to 12%. Novels work best with more active than passive voice - "The father beat the boy." or ""The wind broke the vase." You can get away with more passive in technical articles than in material for general audiences.
In any case, use passive voice for a reason. After a series of short active sentences which speed UP the way the brain processes information, use passive phrasing to slow a mental jog. Use the technique to balance a paragraph. Use it in dialogue to define character. Dont use it willy-nilly without thought.