Here is a short list of questions that might help you to learn your landscape!

http://www.growingthehomegarden.com/2008/08/thrifty-gardening-tips-know-thy.html

How much sun do you get in each garden area?
Do you have areas of shade or will your plants need to be sun-worshipers?
What kind of soil do you have? Is it clay, loamy, or sandy? Or all bits of all three? Is it alkaline or acidic?
What kind of moisture can you expect in your climate?
What plants, trees and shrubs are already established?
Do you have a large slope or is it mostly flat ground?
Do you have large areas to take care of or a smaller plot?