There are a few places on the web that have good instructions for how to sort your mailing. Here are some that we have found worthwhile.
One industrious Puritan should find it Easy to stick 400 labels in an hour. We know an organization that sticks 10,000 labels in one mailing! Once a year they get 20 or so people together and prepare their entire mailing in around three hours. They also use the occasion as an opportunity to catch up socially with their friends.