These are my observations from posts that I have enjoyed reading.
1) No spelling and grammatical errors. This one is a basic requirement and will make sure that your article is readable. I know there can be mistakes in my post right here, but hey, I am not saying that this is a good article!!,
2) Avoid use of redundant words. Example: "I basically mean" where just "I mean" would have been sufficient. Do not use more words where fewer would convey the message.
3) Always follow generic statements with actual instances,People like reading stories about other people.
4) Humour always make a piece interesting.
5) Its an art that can be perfected and like any other art requires lot of patience.
6) It is very easy to put in clichés, so one has to be very conscious of that. Clichés cannot be avoided all the time,then they would not be clichés would they?