Artist Trading Cards are wildly popular. Although they are intended to be traded as the name would indicate, many painters sell them. Whatever your goal in creating them, here are a few things to keep in mind.
Paper is important. No matter what type of paint you are planning on using, be sure that you have the right type of paper. Strathmore sells artist trading card blanks online. They are the standard two inch by three-inch size. Illustration board, vellum, Bristol and watercolor cards are available. You can always make your own by cutting down any of the aforementioned papers to that size.
Working in miniature has its own challenges. Once you have settled on the type of medium you will use and the correct type of paper, it is time to choose a brush. I prefer a fine detail brush over a liner. Liners tend to be longer and more difficult to handle on a small surface.
Keep two containers of water handy. Use one to clean your brush and the other to add water to the paint should you need to thin it out. Of course, make sure that you have paper towels or the like to dry the extra water off the brush.
I like to have a scrap piece of paper to make a color swatch before I begin. If you are in the middle of a project, it is so easy to pick a color that looks right and once it's down find out it isn't the right one. If you do find yourself in this situation, there are two ways to fix it. One is to use gesso. Because of its opacity it is able to cover most mistakes. The other possibility is to work with what you have. If you are using acrylics, a bit of white mixed in will lighten a too dark mistake. If the color is too light, a bit of black may compensate. Make sure you mix the paint on the side and then lay it down on the work.
ATC's are a wonderfully satisfying project largely because they are a quick way to paint and not as intimidating as a large canvas. When you are finished, you may want to spray them with a fixative and definitely cut a piece of cardboard to size. Thin plastic card holders and the ones that hold baseball cards are great for keeping your art safe yet accessible.
When you have accumulated a half dozen or so, they make a great mini-gallery for you or a treasure you can swap with someone else.