"Do you want some free points?"
I was stood in the grocery store yesterday and I didn't have my phone with me. I needed to use the store's app on my phone or use a loyalty card to get a discount on my shopping. So I turned to the guy at the next self-checkout machine, pointed to his loyalty card and asked him, "Do you want some free points?".
The guy didn't hesitate. He swiped his card and got a bunch of free points from my shopping. I then thanked him and explained I needed his help because that's the only way to get a discount on my shopping.
But I didn't lead with that. I didn't say "Hi sir, can you help me for a second?". Because people don't always want to help strangers. People are busy and don't have the time to stop what they are doing, most of the time. So I led with the offer and what was in it for him.
The lesson here? If you want to convince someone to do something, lead with what's in it for them, not what's in it for you.