The basic purpose of a transition is to serve as a topic sentence. It should give enough direction so the reader knows what to expect. When your essay is following not only a chronological order but also a single train of thought, the paragraphs may flow smoothly anyway. Transitions become more important when you move from theme to theme or experience to experience. The strongest transitions will not only introduce the ensuing material but will draw connections to prior paragraphs. The reader has to know both where he is going and how it relates to where he has just been.

What Not to Do

The most common mistake-other than omitting transitions altogether-is a reliance on words like "also" or "further," which do not provide any thematic link. Using such substance-less transitions makes your essay sound like a list instead of a logical argument. For example:

Bad:  "Volunteering at the local hospital also provided a great deal of useful experience."

Good:  "Although working at St. Anne's soup kitchen provided insight into the beneficial nature of community service, longer and more in-depth interactions with individual patients while volunteering at Mercy Hospital proved to me that I want to pursue a career in public service."