1) You should chose a topic you feel strongly about and are knowledgable on. There is no point in writing about flowers if you have no interest in them and you do not know the difference between poppys and roses.
2) Research is the key for factual articles. I suggest using ask.com or other useful search engines such as google.
3) Write short concise paragraphs. A bulk of sentences may put some people off. But remember if you article is only 100 words long then it is probably not worth writing. I suggest at least 300 words.
4) If you want many page views, and page views mean earnings, then pick a popular topic that you think people will want to read about.
5) Do not drag an article out to make the required number of words, you should get to the point fairly quickly as your reader will lose interest.
6) Make sure your article has a body to it, by this I mean an introduction, which can be a few lines, a main body, which will make up the bulk of the article and then a suitable concise conclusion to finish.
7) Finally and most importantly check for spelling mistakes and grammar errors. Sometimes it is difficult to notice your own spelling mistakes, I recommend that you get a friend to do this for you.
Another quick tip is to read articles published by top authors in your interest area, I find this helps me to improve my articles.