One of the greatest things I did with my kiddo before he was baptized was have Family Home Evenings about getting baptized. This helped prepare him and make it so he was better able to make the decision to be baptized. Here is the list of some of those Family Home Evenings:
Family Home Evening on July 2014 Primary Theme: We Become Members of the Church through Baptism and Confirmation
Family Home Evening on The Sacrament Helps Me To Renew My Baptismal Covenants (Faith in God Book Activity)
Sharing Time Ideas that could be adapted for a FHE:
LDS Sharing Time Ideas for May 2015 Week 4: When I am confirmed I receive the gift of the Holy Ghost.
LDS Primary Sharing Time July 2014 Week 2: I become a member of the Church through baptism and confirmation
LDS Primary Sharing Time July 2014 Week 4: I can know the truth through the power of the Holy Ghost.