Participle sentences
Participle sentences are the most common stumbling block I see in early drafts. Not only do such sentences allow dangling participles to creep in (where confusion arises because the subject does not relate to the verb), but they can also produce a jarring cadence when two or more participle sentences occur close together.
"Driving down the road, the dog stuck its head out the window. Gripping the steering wheel with one hand, Mike grabbed the dog's collar. Barking in fright, the dog pulled loose."
When you find yourself using participle sentences, you will usually see that you are attempting to cram two or more actions in one sentence. In some cases, as in the first example above, you can separate each action into its own sentence.
Where the two actions are occurring simultaneously, the clearest solution is to move the subject of the sentence up front.
"Mike gripped the steering wheel with one hand and grabbed for the dog's collar."
Alternate the lengths of sentences
Read your work aloud. A piece that sounds stale and flat often has numerous lengthy sentences with no break, while a choppy, jarring piece might have too many very short sentences.
Mix it up by finding the most important statement in your piece and using the opposite style to highlight it. A short sentence will stand out in several paragraphs of long sentences. A longer sentence in a pacy, active sequence of short sentences draws the reader's attention as they pause to take a breath.
In the same way, you can speed up the rhythm of your action by introducing a few short sentences, or slow it down by combining sentences. Readers respond to rhythm that mimics the pace of the action that is being described.
Compare ~
"Mandy ran through the mall, pushing past the throngs of people. She saw her pursuer reflected briefly in a glass door, as she unlocked the safety panel and hit the fire alarm."
To ~
"Mandy ran through the mall. (quick action) She shouldered through a throng of tourists, her heart racing as she caught a glimpse of her pursuer reflected in the glass door ahead of her. (being slowed down, but contrasting with the short sentence) She fumbled with the key as she unlocked the safety panel. (a little faster) "Come on!" she breathed. It slid open. Mandy hit the fire alarm. (three short bursts that could easily be one compound sentence, but, as such, would not convey the energy that the short sentences allow for.)
Tongue twisters
Note, also, the alliteration in the second sentence above ("She shouldered", and "through a throng") that also serves to slow the rhythm down and make the reader feel Mandy's frustration at being trapped by the tourists.
Use tongue twisters like these with care. Usually, you would consider changing some of the words so that they don't jar the reader. In the right place, though, they will slow the reader down as the brain tries to work out whether it read the sentence correctly.
To learn more about how word choice and combinations can bring your writing to life, try some exercises in the more controlled poetry form: Writing Your Rhythm by Diane Thiel, or The Practice of Poetry : Writing Exercises From Poets Who Teach by Robin Behn
