Remember, your personal statement is 'personal' in nature so it is in your best interest to be sure that all the information you provide is in fact your information. By starting with one sample and taking some ideas, then moving on to another and taking additional ideas, and so on, you allow your true self to come out in the finished product and this will give you the best shot at gaining access to the school of your choice.
The first step in preparing your Graduate School personal statement _ Take the time to research and understand the doctrine and mission of the school, this will be intrinsically reflected in your writing and prove you are addressing your statement to this particular School. However, do not parrot their own information back to them _ they already know it and this leads away from helping understand YOU. Understanding the audience for your statement will help you to develop compelling content that grabs their attention.