Don't mistake a lack of response for a lack of interest in your post. For the most part, shorter posts that take up no more than one screen will have a better chance of being read than a longer post. Keep your tone conversational. If you think someone has misunderstood what you've posted, ask first. When you are making a longer post, be sure to break it up into several shorter paragraphs.
Short paragraphs are easier to read than long blocks of text.