Don't use </br>. Do ensure you have the 'HTML Related Options' in your User Display Settings set to most strict.

Perhaps suggest OPs run their code through Perl::Tidy in the 'Good coding practice' section.

s/good formulated question would garner/well formulated question will garner/

I'd downplay the node rep (voting) issues and focus more on speed and quality of reply. Many posts are (at least initially) one off posts - node rep and the XP game are thus not compelling behavior modifiers. ;)

Keep in mind that the people most in need of this advice won't see it until someone links it in a reply. Maybe it is worth mentioning that registered users can re-edit their nodes?

Otherwise, nice node!

Update: added section on re-editing nodes.