Student's guide to writing college papers, Fourth edition - Kate L. Turabian 2010

Check your paragraphs
Revising your draft
Writing your paper

Each paragraph should be relevant to the point of its section. And like sections, each paragraph should have a sentence or two introducing it, usually stating its point and including the key concepts that the rest of the paragraph develops. If the opening sentence or sentences of a paragraph do not state its point, then its last one must. Order your sentences by some principle and make them relevant to the point of the paragraph.

QUICK TIP

Avoid strings of short paragraphs (fewer than five lines) or very long ones (for most fields, more than half a page). Reserve the use of two- or three-sentence paragraphs for lists, transitions, introductions and conclusions to sections, and statements that you want to emphasize. (We use short paragraphs here because our readers sometime need to skim sections, not a consideration in research writing.)