You only have a certain amount of time to connect with your readers on a website, so make sure you...

1. Plan your piece, get all the information you to in there - no more, no less.
2. Keep it short - You should write your article, bin half of it, bin half of what's left and then that's as much as you need ;)
3. Get to the point. You don't have time to waffle.
4. Be clear. There's nothing worse than proclaiming to be an authority then demonstrating that you don't seem to know what you're talking about.
5. Stay focused and don't wander off topic.
6. If at all possible back up your points with references, on the web this means use links.
7. Reinforce & remind - here we're talking about writing articles for the web - don't forget that ;)
8. Write for your audience it is they after all who will be coming back for more so make sure its good enough for them.
9. Engage your readers by giving them the knowledge they seek so they go away satisfied they've gained from your piece.
10. Get Feedback and act on it. Even negative feedback gives you the opportunity to improve so it's actually more positive than it is negative.