Regularly send handwritten notes to your business clients and your other relations to strengthen the bond. Develop a system which reminds you to send something valuable to this network at least once every four months. Send them postcards when you are away on vacation. If you have to buy a few hundred postcards and spend an hour writing, don't worry. This is an exceptionally good investment of your time. Another idea is to send a recent article of interest to your contacts with a handwritten note saying that you thought this would interest them and that you continue to value their friendship. Relationship building should always be a central focus whether you are a CEO, a student, a salesperson or a parent.