Here is a useful tip from energysavers.gov:

Solar heat absorbed through windows and roofs can increase your air conditioner use. Incorporating shading concepts into your landscape design can help reduce this solar heat gain, reducing your cooling costs.

Shading and evapotranspiration (the process by which a plant actively moves and releases water vapor) from trees can reduce surrounding air temperatures as much as 9° F (5°C). Because cool air settles near the ground, air temperatures directly under trees can be as much as 25°F (14°C) cooler than air temperatures above nearby blacktop.

Click the link above to read more about landscaping techniques for your home.