Give them time to ask questions. If you don't know the answer, tell them you'll find out and get back to them in two days or less. Also, thank them for the opportunity to talk with them. Be sure to get their name. Maybe they can be helpful to you next time.
Effective advocacy is all about building good long-term relationships.
Do this within two days. This little courtesy helps more than you might think because so few people do it anymore. By doing it, people remember you with respect. Work with others, whenever possible. Two or more heads are better than one.