A sentence should not only make sense but should also be capable of standing alone as a complete unit; a good sentence will also have shape and form.
Sentence length is important in any piece of writing. While there are no set rules for this, shorter sentences are better. If the length of an average sentence is 15 to 20 words, then it’s best to vary length around this norm rather than sticking to a single pattern which can become monotonous.
If you want to introduce an element of pace or urgency to your work then very short sentences are ideal. But be careful not to overdo this staccato form: a succession of short statements can become just as tedious as long sentences.
Longer sentences can be useful but must retain logic and clarity; the great danger with longer sentences is that the message becomes blurred and readers lose touch with the first part of the sentence by the time they have reached the last part. This last, for example, was 45 words long, but I hope that the message retained clarity. When you edit your writing, work on your sentences; some might need shortening and others lengthening.
Another aspect of sentence structure is rhythm. This is not easy to teach; it is more instinctive and comes from experience, both of writing and reading. Good writing has a certain rhythm which, unlike poetry, is not regular or repeated; more a subtle satisfying sequence of sentence flow. Such flow makes it easier to get the sense of the piece at the same time as enjoying the reading.