Variety is the spice of sentence structure, and in more ways than one. Understanding how sentences are structured and how to add variety to them can amp up your writing to make it not only more readable, but also more interesting on a fundamental level.
When writing, try to avoid repeating the beginning of sentences with pronouns or articles. Look through your recent work. Are the sentences repetitive? Do they all start with "she" or "he"?
This indicates a repetitive sentence structure that can end up "thudding" in the reader's ear. I.e. it can make the sound of the sentences repetitive and boring instead of striking and engaging.
For example : She thought he should have worn aftershave. The smell would always entice her. She never understood why he didn't go the extra step to make himself attractive.
Now, read it this way: Why didn't he wear that aftershave I got him last summer? She shook her head and looked at him as he concentrated on driving through the snowstorm. Taking that extra step wouldn't have killed him.
See how varying the sentence structure forces the writing not only to be more interesting, but also provide more information? Consider each sentence and look at it in relationship to the other sentences.