Don't trim your plants into geometric shapes or force them to meet otherwise unrealistic expectations. Allow them to show you their natural beauty. Compose beautiful spaces with nature, don't work against it. I love the look of rough-cut stone steps, casual roof gardens, and (climate-allowing) moss.
Top image from .free-hdwallpapers.com, middle image from westphoria.sunset.com, and the bottom image is from frustratedgardener.com