TT reader Tsuyoshikentsu emailed me about this article on Wizards of the Coast’s official D&D site: Adventure Builder: Writing Your First Adventure (Part 1 of 6), by Wolfgang Baur. (Thanks, Tsuyoshikentsu!)
Since it’s geared towards writing your first adventure, Wolfgang spells things out in detail. For example, he recommends including two skill-based encounters, two magical encounters, one mook encounter and so forth — essentially, he provides a script to follow.
While this won’t produce the most original adventure, there’s some solid advice in there — like giving every PC a chance to shine, not including too many red herrings and using a simple backstory. (Nor is it all aimed at D&D, either.)