Curb appeal, depends on how much you wish to spend and how much upkeep time you will need to mantain the landscape after the Landscaper has left.
Adding minor additions can enhance the outer looks for small cost, like this Blue Spruce to the side of this home. Keep in mind the selection as in 30 years this may have to be remove due to the size after such time.
Back yard scapes can enchance the your mood allowing the peacefulness within to put a smile on your face. The flow of a waterfall, or running water, the small of scented flowers, the laughter of children playing, or a loved one near by. Your feelings and emotion allow you to relax, take in, and enjoy.
Color is another way to enhance the curb appeal, paints can used. Many paints that were mixed by mistake can be a very inexpansive way to add color and brake up the solid green look. Like solid cement walkways and potios in the middle of the city, the use of color beds. Even the animals feel at peace here.
Making minor additions a little at a time, picking the plants that do well in shade, or full sun or those that can grow with out regualar waterings. Like this home, in Lancaster CA, where temperatures are dry and hot. A water saving drip line to allow plants to servive and live a long and normal plant like life.