Oh! Oh! I know how to do this! 🙂
The optimal length for an article is 2500-3500 words. Your editor often goes over that, much to the consternation of the art director, but generally, if the words tell a good story AND there are enough good photos to support it, we make it work. The rough ones for us are short articles with a ton of great photos, or long articles with a paucity of photos.
As a writer by trade, I suggest you make an outline. It makes it really easy to write without forgetting things during the process. You want an introduction, something to explain why you chose to build the subject. That might be something historical, something about your relationship to the kit, something about what you hoped to try out, etc. Then, maybe a bit about the kit, then the build.
While you're building, take plenty of photos. Take them at the highest resolution you can; print is unforgiving to low-res images. You don't necessarily need a professional camera - my last several articles were shot entirely with my iPhone. (Richard Marmo's tutorial on model photography that appeared in the Journal is great if you have a better camera and a tripod. I learned to use my expensive Nikon by following his instructions.)
I strongly recommend including things that went wrong. My article on the MiG-15 in this issue is an over-the-top version of this. We're modelers, and we like the process of modeling, so the pitfalls, faux pas, mishaps and mess-ups are both educational and entertaining. The secret to being a good modeler is learning how to fix your mistakes!
Write it up (preferably in Word or some other mainstream application - don't make us hunt for compatible software!), and send it off via email to either John Heck or me (we can coordinate between ourselves). If the photos need help, John will make suggestions. If the words need help, I'll handle it. Generally, there's no need for me to send it back for a re-write - I think I've done that twice in 13 years. Writing is a team sport, and I'll do my part in the editing phase.
Expect an email from me with seven questions - I use that to create the bio.
That's about it. We want a good mix of subjects in the Journal, and we always especially need more cars, ships, sci-fi and figures to keep the mix reflective of the membership. So, write, everybody! And thanks!