My favourite technique for chipboard is to colour with watercolour pan paints. Any pan paint is fine - here I have used an inexpensive childrens set, but I also love Prima Watercolor Confections. There is no need to Gesso first - just paint direct onto the raw chipboard. For this butterfly I start by painting a dark blue in the centeradding progressively lighter shades of blue as I move out to the wing tips (for an ombre effect). Add a second coat of each colour if necessary.
I've used these butterflies and a numeral on a 50th birthday card for my friend :)
Imaginarium Designs chipboard I've used includes
50th (small) : code IDN0062
4 small butterflies : code IDT0014
All of my photos have been printed on an Epson XP-600.