Learning to create varied, informative and interesting sentence beginnings is one important skill to develop in order to build sentence fluency. A series of sentences that start with the same word will begin to sound stilted and dull. To create sentences that flow, start sentences with different parts of speech and with clauses whose functions in the sentence vary. For informative or journalistic writing, put information up front. In narrative writing, start sentences in ways that catch the reader's attention or prolong dramatic tension.
Appropriate and varied sentence lengths also help to create a balanced, flowing piece of writing. A common fault in weak writing is a series of short sentences in a row. This can easily create the choppy rhythm usually reserved for elementary school reading books. Conversely, long and winding sentences may be hard for the reader to follow smoothly. To create clear, flowing prose, it is important to develop the ability to break up long sentences and allow a natural variation in sentence length.
Failure to vary sentence structures can result in writing that is either choppy or meandering. The sentence structures you use will also determine how easy it is for the reader to understand a piece of writing. It is helpful to envision sentences as having a main section (called the independent clause), with additional sections (called dependent clauses) that you can add to the beginning, middle or end of a sentence, usually with commas. Help your writing flow by varying the number, length and position of dependent clauses.
The acid test for sentence fluency, of course, is reading the text aloud. As you read, watch for the rhythms and sounds produced by the choices of punctuation and vocabulary. Words that use alliteration and assonance will draw attention to a particular section and can give your writing a poetic feel. The length and complexity of words and the patterns of stressed and unstressed syllables will also affect the feel of your writing, allowing you to create staccato, rhythmic or natural sound patterns.