Prepare a newsletter to your existing mailing list that you can send out on the same day you activate your campaign.
Tell people why you have started the campaign, why it’s important and what the money will be used for.
Once the campaign is live send them new information about the process and thank those who have supported the campaign. Many people need to be reminded several times before giving to a campaign.
Send a thank you to all who have supported you at the end of the promotion. Preferably with updates of what the money will be used.