A newsletter is not the place to try to show off how much you know. Write at the readers' level level of comprehension or below. If your audience is representative of the general population, write at about a 5th grade level. There are several different formulae to calculate the reading level. Use white space and clipart or photos to break up the page.
Nothing is more daunting or boring than a page full of text.
Read it out loud. If you read it out loud and the sentences flow easily, it will be easy to read. If you find yourself tripping over your words, the reader will probably stumble as well. Put it down for a couple of days. But try reading an article you wrote last week.