The only thing to do to really try and improve this is to offer some kind of hint when the user is entering a subject. My experience with these hints is not really that fabulous though... not to mention the fact that it ends up causing more and more clutter with every hint you have to add
One thing we've done is link up the How to get the most out of your Forum Post guide from the forum. In the new design I think that might even be linked up on more pages than it already is. That link is to a wiki travel guide, so by all means, feel free to edit it and improve the wording/suggestions for future posters!