- Where too many consecutive sentences begin with the subject immediately followed by the verb.
- Where too many nouns are immediately preceded by an adjective.
Loretta ran through the thickening twilight, calling his name. Her breath came in painful gasps and her straggly hair was plastered to her sweaty forehead. Her legs were tiring now and black specks rained across her vision. Thick clouds were gathering, rolling in across the darkening moors. Loretta collapsed, unable to run any further. Laughter rose up in her chest. "That's like bloody Wuthering Heights, you stupid woman!" she cried, "Except badly written." The looming rain-clouds opened and she was soaked within seconds. Loretta didn't care. It would make her look much sexier when he came back, as she knew he would. She adjusted her silken top somewhat, and waited.Lazy, yes?
Now, don't become too paranoid about the subject+verb sentence starts: this is the natural way in which the English language works. But do try to vary it a little. Certainly make sure you don't have too many consecutive She/he/name+verb or anything that sounds too obviously similar.
The easiest way to vary this is to make the occasional sentence start with a participle. For example, "Adjusting her silken top somewhat, she waited." Or a subordinate clause, such as: "As Loretta ran through the twlight, she called his name."
The obvious way to avoid the repetition of adjective+noun is simply to use fewer adjectives and make them work harder. You can do this by choosing stronger verbs, or by trusting your reader to understand - for example, in the second sentence, at least one of those adjectives is redundant. (Straggly, I suggest.) You don't need looming rain-clouds because you've already said they are gathering. In the last sentence, you could have omitted silken and said something like, "As the rain fell, the silk clung to her body." Or something.
There's an easy way to spot any of this: read it aloud and listen for the jarring repetition of pattern.
Here endeth today's top tip.