Acrylic paints designed for use on ceramics can be purchased from a craft store. These paints require no preparation of the ceramic object other than a clean, dry surface. Be sure to remove any ceramic dust left behind in the casting process before you begin painting. If you're mixing colors, try mixing a good amount ahead of time and storing it in a separate container. This will prevent you the trouble of having to mix more before the project is finished, lessening the chance that you'll not get the color right the second time around.
While brushes are the most common way to apply paint to ceramic objects, you can use your imagination and apply just about any painting technique to ceramic as you can to canvas. Consider sponge painting techniques to give your ceramic decorative patterns. You can also use a stain. Another technique that works well on ceramic that hasn't been fired is etching. Use a sharp knife to scrape designs into a painted ceramic object or to carve raised designs, then apply darker shades of paint in the depressed areas to create depth and shadow in your pieces.
If you want part of your ceramic to be white, use white paint rather than leaving the ceramic unpainted. This will give you a consistent finish. You can also paint white over the white bisque as a base, then apply special effects spray paint such as antique gold, touched up with black acrylic, or a spatter finish that gives your piece the look of old stone. You can buy special effects in hobby and craft stores and even in some hardware stores. Another technique for ceramic painting is to use dark base coats of paint with lighter brush strokes of the same color.
Glazing isn't necessary if you want a matte finish; however, dishes, vases and any ceramic project that needs to be waterproofed will need a coat of clear ceramic glaze. You can purchase the glaze at craft, hobby or ceramic shops. Consider adding a multicolored pearl glaze to enhance the colors of your finished piece.