First things first
First thing is to understand that patios and terraces are living spaces relax and enjoy fresh air and good weather. Therefore, it is a place where all senses work together, to feel a warm breeze while having a nice glass of wine, smelling those peonies and roses and enjoying the scenery.
color and layout
The correct use of color is a basic to create an atmosphere that is relaxing and vibrant at the same time. Earth colors are the preferred option, they work like a calming balm, and an empty canvas to enrich with other colors that are more vivacious. Natural textures like fibers and clay are a lovely way to have earth tones in the patio, combined with soft wood and stones like pink marble or arabescatto will do. We can use accent color in accesories like cushions, flower vases or even table ware, the color will depend on your own taste, acid color will be more vibrant while pastels will resemble the mediterranean home style, which is like a balm of serenity. You can use a home design app or hire 3d rendering services to have a glimpse of how your Project would look like.
Now, a patio is a place to entertain so we can use the same guidelines to decorate a livingroom, of course there are differences. Specially in regards of the materials, we have to make sure the patio furniture is designed for outdoors, with correct materials that is quite resistant to the sun light, rain and even extreme temperatures.
But the scenery is the key to ensure that a patio, big or small, is a nice place to be. Maybe you have a huge lawn in a country house, or just a small patio in a town house. There are many exterior home design styles, the English garden style is actually very compatible with American homes, and it consists basically in a lawn sorrounded by trees and schrubs, the idea is to create a natural and wild appearance, this is a premise of the romanticism in the XIX century. One example of this are the Buckingham palace gardens, there are different sections and as further as you walk from lawn right in front the palace, everything gradually becomes a bit more wild. You can apply this, have an empty lawn in front of your terrace but surround it with different kinds of trees, schrubs and flowers using levels to design it, first the trees then the bushes and then the smaller plants like hydrangeas. You can decorate it with a little promenade.
For a small patio, you can use accesories and decorations to make it more sumptuous, like a small fountain, marble vases, also you can put plants in eye catching flowerpots. Remember that the furniture also has to fit in the space, so it has to be small so the proportions match.