One of the unspoken secrets of the pros is using layers in their designs. If you have any doubts about that, go to some of the most exclusive and expensive neighborhoods where you live and really look at the differences in those landscapes and the ones in the more middle-class areas. Big difference. Right?
You can look at world-class and famous gardens such as Canada's Buchart Gardens or the Missouri Botanical Gardens as well and you'll see it there, too. It's layers!
Of course, there are many other elements about a design other than just using layers of plants, but this is the one that makes for a spectacular garden and landscape versus one that is attractive but somewhat mundane.
In using layers, you'll find for example, large shrubs in the background or maybe some of the tall slender Italian Cypress-type trees, but in every part of the design there will be other shorter plants and flowers in front of those.
So if you think your small little yard can't look amazingly beautiful and get a lot of attention from the neighbors, think again!
One example that could be used in a smaller landscape and get that gorgeous, lush appearance would be to have the tallest shrubs say, against your back fence (maybe Red-Tipped Photinia or a Privet Hedge with 2-3 tall cypress-type trees either in front of the hedge or off to the side, and then in front of that could be some Japanese Boxwood, kept to about a 4-6' height (depending on the height of the hedges in back) and then to compliment the layers, maybe a statue or birdbath surrounded by smaller shrubs (such as dwarf Youpon Hollies or dwarf Pittosporum or flowers as an alternative).
Corners are wonderful for creative landscaping. One of the favorite corners in my own landscape is one between my back gate and the house. I've put two 4x6 pieces of trellis there (one on the fence, the other on the house to make a corner of trellis) and it is covered with lush beautiful ivy. In front of that is a birdbath on which I cemented a 20" angel, and the birdbath is surrounded by small Youpon Hollies flanked by a beautiful hot pink Sage Bush and deep green Lariope. Simple, layered, inexpensive, but striking and very finished looking!
If you have a center-of-yard type garden design such as flowers or a ground cover around a tree for example, and you have several plants there, the same "layering theory" would apply: large plants nearest the tree and smallest at the borders of the planting.
I hope you have found this theory helpful and will apply it in your own landscape design. I think you will see an immediate difference!