I also call this the “Who do you know strategy.” When developing a business strategy, we go to our weak link network. Write a custom email to each person in your network and If they know someone who could be a prospect, invite the weak link to have a personal phone call or meeting. You can then discuss their connection and the best way to make an approach. There are two ways to make the introduction and referral: 1) In-person or 2) by email.
Weak links are people in your network you don't connect with frequently.
These are your best referral partners.