Monogram mugs are currently a big hit as well as almost anything with watercolors and word-art. Remember that trends are great, but use them as inspiration to design with your own uniqueness. Check out places like Etsy and Pinterest for more of what is trending.
When designing a mug, I use a 9″ X 4″ rectangle as my template for an 11- and 15-ounce mug. I design in Photoshop, but you can do the same in any graphics program you use, such as Silhouette Studio or Inkscape. When looking for graphics to design with, there are two places I often use: Design Bundles and The Hungry Jpeg.
-Cheryl Kuchek, Just My Imagination DeZigns