I made the body of these mugs with Hawaiian Red and painted the inside of the bowl with white slip (playing it safe since I wasn't sure which of my glazes would show up on the dark clay). I applied a design of white slip on the outside and when it came time to glaze, I made the inside of the bowl a vivid color that contrasted with the deep brown of the outside, which I covered in clear glaze to avoid the unpleasantness of bare clay scraping against teeth.
I'm going to make these bigger next time since they only hold around 6 ounces. I was going for 10 but I haven't learned to account for shrinkage yet. It's all a learning experience!