Great advice Theresa!!
Lisa turned me on to Make your content presell and that has really helped me. If you haven't downloaded it go to
http://mycps.sitesell.com (not an affiliate link, by the way) It has some GRRRREAT tips for writing content.
I agree with Theresa, there's no right or wrong length for an article. An article should be as long as it needs to be and that will vary from topic to topic. There was another topic on here recently about this very subject and someone gave a good suggestion of breaking your articles up into sections or separate pages if they get too long.
But the key is to be helpful and not be afraid to share your personal experiences in your writing. Your writing should be conversational as if you are talking to them and the great thing about the web is that it is much more relaxed so you can use ellipses, short sentences and very casual writing.
Try to stay away from phrases like "You all know...." or "Everyone here should know" Try to keep it active and say things like "You know..." or "You should know..." That helps the visitor feel you are speaking directly to them.
I have to catch myself on that a lot.