Keep your sentences sweet and to the point. I understand that sometimes sentences run on a bit, but never to the point of causing the reader to run out of breath. A good rule for this. Keep your sentences no more than 7 words, followed by a break. Well, you could use a period, comma or anything else that allows the reader to breathe.
Text size is of importance.
The size of your text will also help contribute to the readability of your content. By having text that is too small, you are forcing those of us who use high resolution monitors to get within inches of the screen. Many of us won't do that. They are an important part of your text. By using headers, you can let a visitor know what the text below is about.