The simple definition of "Collage" means the addition of materials such as paper, fabric, clay or other foreign objects to the surface of a finished picture. Some artists will even continue to work on that surface with paints after the collage has been finished.

• Cut paper collage: In this instance cut paper itself holds center stage as the collage material. The paper can be either cut up painstakingly with an X-acto knife or torn by hand. The work is then mounted on board and then lit to best showcase its dimensional qualities.
• Photo collage: Photographs can be used in the same manner as paper to create collages.
• Mixed-media collage: In the case of mixed media collage, many diverse materials are often brought together to create the art. Photographs, newspaper clippings, magazines, old catalogs, cut paper, and "found" objects often form the background of the collage. The artist will then draw directly on this surface using pen and ink, watercolor, gouache, and pastel. The end result is often a wonderfully dynamic interpretation of time and place.
• Computer Art: Similar to traditional collage in that a combination of materials are combined to make the finished artwork. These materials include photographs, drawings, newspaper and magazine clippings, and found objects. The big difference between digital collage and traditional collage is the way in which the materials are combined. In digital collage, the artist uses a computer instead of glue and an X-acto knife. First, items are scanned into the computer. They are then manipulated using computer software. The most popular software used for this process is Adobe PhotoShop, which allows the artist to layer photographs, drawings, and text all in one image. There are other programs, such as Adobe Illustrator, which allow the artist to make drawings and paintings directly onto the computer screen which mimic more traditional art mediums.

Gouache is an opaque watercolor paint that is used in the same way as watercolor (see watercolor definition). Unlike watercolor, gouache is not transparent, instead, it is built up in layers to a matte finish.

Oil paint has great texture and vibrant color. It can also be be thinned to whatever the need of the artist. As a result, it has much to offer the illustrator. The actual color pigments are very finely ground with good quality oils so that the concentration of color is extremely high. These colors are used in conjunction with thinners and a medium for great versatility. Unlike the fast drying acrylics, however, oil paints take a long time to dry.