For this reason I am offering a workshop on mixed media techniques in which we use the heart as the image. It is called Light Hearted, and I'll be offering it along with other workshops at Art and Soul this May in Colorado Springs. Read about it here. See my other workshop here.
In the video I am using Utrecht acrylic matte medium to adhere the collage to the substrate, and also for the top coat. It is my favorite matte medium for collage. The markers are Posca, which are opaque paint markers.