We personally feel that the coffee mug design must be attractive but it should also be to the point as well. It does not have to be wordy, it does not have to have big design elements, caricatures, or patterns on it either but whatever you choose to put on the coffee mug as your design, it must be visible enough to be seen even from a distance too. Another thing that you must keep in mind before finalizing the design and printing is if it will be washable, permanent, or dishwasher safe. You would also like to see if the coffee mug can also be used in the microwave, you know so that all your fronts are covered and that you can market the product well.