As I noted earlier this month, about three weeks ago I began really diving into the Open Call submissions and getting back to authors with feedback about their work. I'm more than halfway through the pile now, and so far it's been really productive. It looks like we might see Open Call authors showing up on the front covers of scenarios in a matter of months! I gather many of you are working on submissions now, and I'd like to share a few recommendations and tips that have come up frequently.
Scope: A Quest is a quick, self-contained adventure that is restricted to 2,000 words or less. Keep this in mind when outlining and writing a Quest, for it can be really tempting to try to squeeze a full scenario- or module-worth of ideas into this short format. The most successful Quests typically have a combat encounter and a brief non-combat encounter, and some are able to manage two combat encounters with style. I find that when a Quest tries to fit in three combats, it often comes at the expense of the background, area descriptions, or some other important section.
It's certainly nice to have a definitive end to a Quest, not a "to be continued." Sometimes longer adventures have that type of cliffhanger, but I'd rather your submission leave the players high-fiving and knowing they won rather than looking worried and feeling like they barely scratched the surface of the story.
Organization: Be sure you're modeling the overall organization of your submission after other Paizo adventures. Ambush in Absalom is an excellent reference for making sure you have all of the important pieces in the right place, including the Summary, Getting Started, and Conclusion sections. Where does the "Creatures" header appear in an encounter? What types of information appear in the "Development" section rather than in the room description? The more of this that an author can internalize and demonstrate, the easier it is to develop and use that person's work.
Subtiers: Pathfinder Society scenarios use a system of tiers that enable play at two different level ranges (e.g. Subtiers 1-2 and 4-5). With the exception of several early scenarios, every such adventure's subtiers are three levels apart, so it's important that you design your encounters so that the difference in the two subtiers' challenge ratings is three as well. That means if the lower subtier is facing a CR 3 encounter, the higher subtier should be a CR 6 encounter (not a CR 5 or CR 7).
Remember the Players: Keep your audience and the game format in mind when creating your stories and encounters. A Pathfinder Quest should be approachable enough that a group of somewhat experienced players are likely to succeed, so I would avoid including really powerful combats that are likely to devastate the PCs in a round or two. This is especially true for Subtier 1-2, where it is possible to leverage the challenge rating system to make a very effective yet low-CR creature that deals an average of [an average PC's hit points] per swing. Table 1-1 on page 291 of the Bestiary is a great resource for judging whether your NPCs are a reasonable challenge.
On a related note, also remember that the players are agents in the story limited only by their creativity. Unlike in a video game that presents an uninterruptable cut scene, the PCs have the potential to interrupt monologues and intervene when the villain tries to do something dastardly. Writing cut scenes into an adventure rarely goes over well, and it shouldn't appear in your Quest.
Stylistic Notes and Trends: Paizo's adventures tend to avoid future tense, passive voice, and second person references. Exceptions show up in dialogue and in a few other circumstances. If you find yourself using "you" or realize you've written "will" without referring to inheritance documentation or a type of saving throw, it's probably better for you to revise it.
Review Your Submission: Remember that your submission is a reflection of your writing and adventure design abilities. Reading your work out loud or giving it to a friend to read can help pick out a lot of errors, making it easier to wow your reader with your creativity rather than distracting him with grammatical concerns.
Once again, I'm excited to see so many submissions, and I hope that the recommendations above can help many of you create even more engaging adventures. Keep them coming.