'Start in the middle' is only half the answer. An introduction has to teach the reader enough about the topic to care about the main idea (i.e. exposition in fi

'Start in the middle' is only half the answer. An introduction has to teach the reader enough about the topic to care about the main idea (i.e. exposition in fiction). You can start in medias res (a la the iliad) but you may end up circling back in a flashback (a la the odyssey, odysseus telling his journey to menelaos' court). Starting in the middle is great if your reader already knows the backstory, but you alienate everyone but your core audience. That's expensive whether you're writing a blog post or a hollywood blockbuster. It's a fair assumption that your reader came to you on the promise of the title of your piece. You have to fulfill the promise of that topic or at least give a tidbit soon enough that your audience doesn't give up and leave. You can tell a book by its cover because books with misleading covers don't sell. Balancing exposition against delivering on your genre promise is a 'theory of mind' skill that the best writers have in spades. Think of the first 10 minutes of star wars: scary villain darth vader (check) strolling through a sci-fi spaceship (check). Gun-toting strong princess (check) needing a rescue (check) sends her sci-fi robots (check) to get help. Next scene: crappy teenager main character (that's your audience, check) buys same robots. The order of the villain / princess / hero scenes are optimized to serve the 'message for help / hero to the rescue' exchange. If this were a blog post you'd still have that 'problem / solution' structure but in both cases you need to be checking all your genre points and delivering breadcrumbs of the genre or topic that the reader is here to consume as you inform the reader enough to care about your argument.