I've written hundreds of articles for a variety of magazines. Each one has a different set of writer's guidelines. That's what you need to request. These days you can do it by e-mail. In days gone by, you had to send a SSAE to request the Writer's Guidelines. Some magazines actually have them on their web sites along with payment schedules.
Here's an example: http://model-railroad-hobbyist.com/s...ion-guidelines
For those of you rushing out to find an article by me, until recently, I wrote only under a pseudonym and not under my real name. Personal reasons.