Tips for writing articles for publication
1) Aim to write somewhere around 600 words - this seems to be the typical length appreciated by most journals. Check first though - some sites prefer more or less words per article, but it is usually in the suggestions for submissions anyway.
2) Be original, but try to keep a relevancy to articles already published.
3) Check for spelling and the grammar (use a spell checker or whatever).
4) Break the article up into meaningful sections, using headers if necessary, nobody wants to read a thick section of text. I know, I keep doing it myself, but not when it is to be published!
5) It is an article, not an advertisement. So keep the tone down. They want quality editorial, not a sales brochure.
6) Ask the editor(s) if there are any subjects they'd particularly like you to write about - should you run out of ideas.
7) Make sure you retain all rights to your article. Some sites may want ownership of your work, but this is now rare. If you submit to several journals then it is a good idea to make some minor text changes. Roughly a quarter of the text should be different.
8) In return for the content, you should be able to submit a link at the end. Generally this is automatic, but it may be included in an about the author section or similar.
As in all business matters, both sides must benefit from the transaction. The journal receives a quality article that people want to read and hence they come back for more. You gain a valuable link to your site and make your name more widely known. The main key to this is that the articles should be good quality. A journal that accepts any rubbish is probably not popular with the public anyway, so it is a waste of time sending it to them. You will occasionally get articles returned with suggestions for improvement before it will be accepted. This is fine and happens to all of us. It means they take it seriously and are hence probably taken seriously themselves.
If you do write articles, then I would appreciate you sending them to me as well. I will certainly put them on this website for you. Just tell me what they are about, because I will probably not understand them!