So, of course I do my homework trying to figure out which journal is appropriate for which kind of manuscript I've completed. And of course I read sample articles from that journal. After that, though, do I just submit the manuscript? Or do I check with the editor at the email address the journal site provides for questions? And if so, how do I approach the editor? What is a good/appropriate way of "checking in"?
If you have a concrete and simple question then it could be reasonable to ask the editor in advance, for example "Would a mathematical model of the popularity of film sequels be appropriate for your journal", assuming that the answer wasn't obvious. There is no reason to "check in", and it's an imposition on the editor to pester him/her with merely "checking in". Write the paper, make sure it matches the requirements of the journal, and submit it.