First and foremost, your Parent Association should be welcoming the new parents and giving them a chance to connect with the school family, without a discussion of money. However, when it is time to ask for a gift, your campaign should have a New Parents Chair whose job it is to explain the importance of giving, pay attention to them, cultivate them, and get their commitment.
The annual fund letter should come from that Chair, with an appeal that helps the new parent understand the culture of giving. BUT—it may take a while for a new parent to work through the "I just paid you a bunch of money for tuition, and now you want more" mind-set, particularly if the parent is new to private-independent schools. Follow-up will be essential. It is important that the New Parent Chair and volunteers encourage questions, and be available for further opportunities to educate.
A great way to welcome new parents is having a new parents dinner, with a Board member and a faculty member sitting at each table. The Head discusses independent schools and how they operate, while the Board president talks about governance. The Development Director then introduces the idea of a '"department of engagement" in which the parents get involved. The dinner can also include testimonials and a student performance.
Your New Parent Committee volunteers must be able to direct the message to each family, and go the extra mile to help new parents understand the importance of giving in private-independent school. It's a bonus if your volunteers are relatively new, because they have recently been in the same boat, so to speak.
Toward the end of the year, take the opportunity to meet with new parents and conduct something like a focus group. Ask them about their experience as a donor and a volunteer. Find out if they felt they got enough information from you, and if the message was clear. This interaction will help you do an even better job with the next group of new parents.