The Basics
Whether you plan on "borrowing ideas" or plan on creating your own landscaping design, you should have at the very least a basic understanding of the principles of landscape design. This doesn't mean that you have to apply every principle to every part of your plan. But just having an understanding of these principles will help you generate ideas and increase your creativity.

Great landscaping lies in the eyes of the its creator. So, while the principles of landscape design are great guidelines to follow, don't feel like they're the "have to rules" of landscaping. Abstract and creativity are allowed.

A simple way to create unity in your landscape is by creating themes. And one of the simplest ways to create themes is by using a little garden decor. Creating a theme garden is easier when it's related to something you're interested in or have a passion for. If you're into butterflies for instance, you could create a theme using plants that attract butterflies as well as using statues, ornaments, and other decor that are related to butterflies. Unity should be expressed through at least one element in your landscape and preferably more. Using elements to express a main idea through consistent style and a specific theme is what creates harmony.

Simplicity is actually one of the principles in design and art. It's one of the best guidelines you can follow as a beginner or do it yourselfer. Just keep things simple to begin with. You can do more later. 

Simplicity in planting, for instance, would be to pick two or three colors and repeat them throughout the garden or landscape. Keeping decor to a minimum and within a specific theme as well as keeping hardscapes such as boulders consistent is also practicing simplicity.

Balance in design is just as the word implies. A sense of equality. There are basically two types of balance in landscape design. Symmetrical and Asymmetrical. Symmetrical balance is where there are more or less equally spaced matching elements of the garden design. With a garden equally divided, both sides could share all or part of the same shape, form, plant height, plant groupings, colors, bed shapes, theme, etc. You may remember creating something like this when you were a kid in art class at school. Where you take a piece of paper, splash paint on it, fold it in half, unfold it, and then it magically creates an interesting symmetrical design. So symmetrical balance or design is somewhat of a mirror image or reflection.

Putting it All Together

Now comes the fun part, choosing plants and flowers. Attach a piece of tracing paper over your blueprint. By using tracing paper, you can create several different designs and then choose the pattern you like best. Now begin working on your tracing paper. Start with the shady areas. Consider where you want perennials and where you want annuals. Get a list, or better yet, a gardening book with color photographs of plants and flowers that grow in the shade. On your blueprint, use colored pencils to shade the area with the color of the flower or plant you are putting there. Think about what colors complement each other and the height each plant or flower will mature to.

Now move to the sunny or partially sunny areas of your yard. Think about the type of border you want for flower beds or paths. Don't forget to plant for each season. Make sure you have flowers that bloom in early spring as well as flowers that bloom clear up until the first frost. This way your yard will never be void of color.

The final step is to draw in the location of planters. While you may change the flowers in your planters from year to year, they are still an important part of the overall design of your yard.

Once you have your entire yard mapped out, now it's time to begin the work. Don't be afraid to change your plans if you find something you like better. Most important of all, have fun!