Whether designing on a small or large scale, always follow the same principles of balance, proportion, repetition, and variety of form, interesting texture, and a cohesive colour scheme.
To create the illusion of more space, consider a change in elevation. For a small backyard, you may wish to design two or three levels with steps between, giving the appearance of garden rooms. Use layering in the garden to create the interest. For example, under plant Golden Dwarf False Cypress with Blue Chip Juniper, so it emerges from a low blue carpet of a contrasting evergreen texture. You could also under plant a Weeping Japanese Maple with Burgundy Glow Bugleweed.
With a little planning, a small area can be transformed into a collective garden of unusual plants of varying form, colour, and texture. Here are some ideas to get you inspired for your smaller outdoor living space.