Dear Ms. Harris,
Thank you for your kind note and inquiries. 
Most of the non-fiction papers that I review fall into three main categories:
1. Writing assignments (mainly essays of many kinds—argumentative, literary, historical, scientific, etc.)
2. Research (i.e., thesis) proposals and the analysis of a proposed study’s results; also, articles being prepared for submission to various journals, both online and in print.
3. Reflective writings, such as papers to submit to online courses that require responses to discussions, long written assignments, essay-type arguments, etc.
In terms of corrections, the three most important “changesâ€ or “suggestionsâ€ are difficult to determine, as I consider all of the changes I make/suggest to be important, otherwise I would not make them or ask the author to review them. That being said, I do encounter the following issues quite often (not in any particular ranking order):
1. Long  sentences and huge paragraphs: For some reason, in most of the academic and scientific papers I review, the author (or authors) just roll along and ignore periods and spacing (i.e., indents). A one-page-long paragraph is all too common. While the text may stay on topic, the readers still need help in absorbing the information, particularly when it is numerical or the vocabulary is field-specific jargon. So I often divide sentences and paragraphs, as I deem appropriate, to facilitate the “flow,â€ which is a hard concept to define. My goal is to remove all “speed bumpsâ€ for the readers and these bumps include rambling sentences and “wallsâ€ of text. It’s amazing the difference the use of periods and spaces can make, without changing any of the original words. In today’s world, readers “skimâ€ quickly and so the text has to make this possible visually. The use of more subtitles, for example, helps the “skimmers.â€
2. Comma splices and run-on sentences: Both of these issues are related to grammar. I correct a surprising amount of grammatical errors for college-level students and two of the most common are comma splices (and commas, in general) and run-on sentences. You can easily find many examples of both types of errors via Internet searches.
3. Graphics in research studies: For some reason, the principle of “simple is bestâ€ is rarely applied to tables and charts. Authors seem to think that more colors and shapes and lines enhance a chart or table, when, in fact, the opposite result is obtained by this artistry. Certainly a brightly colored chart or table “looksâ€ good, but the main point to be derived from the data is too often obscured. Simple, clean lines; good data labels; and clear titles, sources, and notes make charts and tables readily accessible to the readers.
As for specific examples, I cannot provide any because I would have to use parts of clients’ works without their permission, which would violate the editorial “code.â€ However, thanks to the wonders of online search engines, you can do keyword searches using words from my notes here to find whatever examples you need.
Thank you.