A clear short sentence:

            John (subject)               hit (verb)          the ball (object).

Can become:

In his first Little League game, young John, the coach’s son, hit the ball weakly to the pitcher’s mound, retiring the side and justifying in the minds of all present the thought that John was in the lineup merely because he is the coach’s son.

In standard English, the average sentence is about 17 words. Sentences with up to 25words are much more difficult to understand, and sentences with more than 25 words are extremely difficult for most readers to comprehend. Successful professional writers average in the low 20s.

For your writing:

• Keep to an average of 20 words or fewer per sentence; limit the number of subordinate clauses, phrases and modifiers;
• Put separate facts and ideas into separate sentences;
• Give the reader breathing space;
• Allow the content of your writing to be understood more easily and remembered longer.
•  Use simple language when possible. In technical writing, sometimes you will have to use complex language (beginners will need to know the terminology they will use in their futures); if you use complex language make sure you define the information. We can’t always avoid complex language.

NOTE: This advice is not justification for short, choppy, repetitive sentences.