Sometimes a sentence needs to be clipped.
Sometimes a sentence needs to dance and juke, moving first in one direction and then another, perhaps exploring the white face of a blue jay after noting its dominant blue color, and then coming to a finish in a flourish, perhaps by describing the characteristic flat flight of the bird.
Most sentences need to be medium, with a basic structure and only one additional phrase or clause, set off by commas.
Of course, when writing a first draft you shouldn't worry about the play of your sentences. You should just get it out there.
During revision you should consider a number of things.
• Does this sentence say what I mean it to say?
Consider the following: "I went out to eat feeling sad." This sounds as if the subject of the sentence ate a dish at the restaurant called "feeling sad." The sentence should read, "I felt sad, but I went out to eat, anyway" or "I felt sad, but I still went out to eat." There are other good options, as well. How do you know which to choose? It depends on what works best in the paragraph and what you want to emphasize.
• What is the central action being described? Do you use it as the central verb?
Consider the following: "He is old and walked down to the lake." This sentence could work in some paragraphs, but generally it should be revised to read, "The old man walked down to the lake." The verb "is," in this instance, does nothing more than link "he" to "old." This can be accomplished much more efficiently by simply dropping the word. Some people want to ban the "to be" verbs: "am," "are," "is," "was," and "were." These claims go too far. During revision, you need to look at how each sentence is put together and ask if attention is being drawn to the central action. If this central action involves the use of a "to be" verb, then leave it.
Part 2 will discuss nouns and phrases.