For an excellent overall feel for your garden, you need to focus on three principles: proportion, unity, and transition.
With proposition, you only have to ask yourself one question: does this (plant or object) fits in or is in proportion with the rest of the garden? In achieving a sense of unity with your garden, you just have to ensure that everything is working together and complementing each other. Don’t let one feature overshadow the other. And finally, transition means a smooth, gradual change or shift from one style of landscaping to another.