Paint the pots in hues that complement the rest of your landscaping design. Design ideas for three-tier planters using color include painting the top and bottom one the same color, with the middle an accent color. Paint the rims of all three the same to coordinate them. Use craft paint for terracotta or ceramic pots, and use paint specifically meant for plastic if you choose to use the cheaper pots in your design.
After you have the color base that you want, add more interest with patterns and pictures. Use paint or permanent markers to draw on shapes, borders and pictures. Invest in some stencils if you are not comfortable doing it freehand. Design ideas include pictures of flowers, vegetables or herbs. Use a black permanent marker on an unpainted terracotta pot to draw shapes like triangles, scrolls or others.
Include theme elements when decorating planters. For example, place wooden beads on a wire to wrap around the top of the pot for tribal or Native American design. Place small statues of birds or other animals in the pot. Any small garden decor items can be used to personalize your three-tier planters to fit into the rest of your landscaping scheme.
Create a true piece of art with mosaics. Choose tiles or glass in colors that complement the rest of your garden decor. Mosaic all three pots in the same way, or alternate designs to match your theme. For example, do one in a pattern of red roses, the second in a hummingbird design and the third in leaves. Incorporate any theme by laying out your design beforehand on the pot, using patterns found in craft books, or freehand drawings if you are artistic.