A writer should not rely too heavily on simple sentences and compound sentences, for the effect tends to be both monotonous and choppy. Too many complex sentences, however, can be equally monotonous. If your style tends to one or the other extreme, try to achieve a better mix of sentence types.
Exercise: Sentence variety
Related topic:
Sentence structures
simple sentence A word group consisting of one independent clause and no subordinate clauses.
compound sentence A sentence consisting of two independent clauses.
complex sentence A sentence consisting of one independent clause and one or more subordinate clauses.