If you find your sentences filled with commas, and they wend from one topic to another, then you, like many people, may be guilty of writing run-on sentences.
The run-on sentence is annoying. The run-on is boring. Most important, utilizing run-ons in your work is a sure-fire way of losing your reader.
The run-on works in one instance – if it is part of one of your character’s personality. For instance, if you are writing dialogue spoken by a typical teenage girl, run-ons would be acceptable (“Well, we went, you know, to the mall, and, like, we tried on some clothes and makeup, and then Sheila saw this really cute guy in The Gap, so we went over and like, started talking, and ...” you get the picture.)
Curing a mania for run-ons may be a simple as implementing an outline for your work. Break each topic down into logical, organized subtopics and details. Relegate each thought to a single sentence. When a topic or subtopic requires further discussion, create unique sentences containing each of these details (or group related details) after your lead-in sentence.
If your topic ultimately branches out to other major topics, reference those topics in your initial paragraph, but address them in other paragraphs (or chapters.) This acts as a “teaser” to your audience, leaves them wanting more, and motivates them to read on.
These instructions sound like high school stuff, but I recently edited a college-level text written by a PhD that was fraught with run-ons. The subject matter was economics. The combination was deadly from the standpoint of maintaining consciousness. So for the sake of your readers, form a working relationship with semicolons and periods, and leave run-ons to the Valley Girls.