I'm not sure if "helpful answer" as opposed to "answer" makes much of a difference in answer quality -- I'd believe it helps a little, just don't know that it's been studied -- but a lot of silly stuff like that does definitely make a big difference in response quality on certain tasks. "Let's think step by step:" at the end of your prompt is probably the best-known one: https://arxiv.org/pdf/2205.11916.pdf