Ask if any questions have come up since you last talked. Make sure they have what they need to do the job, and that they're getting the necessary assistance and cooperation from others. Sometimes people are reluctant to admit they didn't understand something, or that they're having trouble. Asking gives them an opening and permission to say so. It's also a way of finding out if someone simply isn't doing the job, before it's too late.
Some people write well, but hate to talk on the phone.
Some people can schmooze anything out of anybody, while others would rather do anything besides ask for donations. Find out what people are good at, and what they like to do, and make the most of it. Make sure assignments get handed out fairly and realistically. Encourage people to take a realistic look at their workload and abilities, and to take on the jobs they can reasonably handle. Give accurate and honest feedback.