Not enough writers know the answer to this question, or maybe just don't think about their audience enough. The answer is always. Always in non-fiction, always in fiction. In non-fiction, you might wonder. Oh yes. For the love of the muses, in graded essays- get the instructor to take it seriously! Even in tags for videos... CLICK BAIT. Your writing cannot impress unless someone actually opens to LOOK. This means you provoke interest at any opportunity. In the title, in the first line, and in the push line at the end of the first paragraph. Do it everywhere you can within reason. Set expectations, but make sure you can deliver. As someone who reviews work, the first line is the one that sets the tone for the review. Did the writer try to grab or not? As a matter of commercial writing, you have six paragraphs to set the hook.
Some editors won't give you that. The first three chapters of a book headed out for representation or publication review should be immaculate. I am stunned by folks that think their work is ready for agent review where the first line is just meh. The first paragraph is blah blah, and the push is just a soggy half-swing. If you want to publish, don't sabotage yourself by not crafting that first paragraph before the fold. Dynamic Beginnings (1 of 2)