How long, how short should copy be? You either get too much copy or not enough; never ever just right. How large do you dare make type, how small? Can you fluctuate type size between panels on a two-fold (3 panel) brochure? Please don’t. Some one has actually given you an item for the newsletter. Do you devote the whole thing to some one’s passion for winemaking? Maybe, if samples are provided, but never mind, not the point. After examining, many (1) of my own brochures and newsletters (also 1) I had figured out a general guideline for copy for a basic brochure and newsletter.
Three panel brochure inside page, with two medium images: approximately 850 words
Three-column newsletter page with one image and one pull quote: approximately 650 words
Now obviously this is just a guide. Both counts are using Times at 12 point. Different type and type size will have different a word count, still, this will give you a ballpark figure to work with.