I used to run a marketplace business and much of my role was getting in touch with partners to get them on our service. Obviously the value we added was key but I started A/B testing email to see if it made much of a difference. I found that the shorter the email, the quicker the reply I'd receive. I worked it up to about a 50% improvement in the end. Honestly I just learned that people want you to get to the point, lay out the key facts and make it clear what you want.

If you know the person look at saving any niceties for after you've made your point. It doesn't look so false if you save any of this for after you've made your request and and you're actually interested in how their job is going.