Your introduction and even your first sentence are the most important part of your personal statement. This is where you can grab the attention of the admissions representative. Make your first sentence unique and compelling. It is recommended that you state in a creative way WHY you want to undertake this field of study in your first sentence. The rest of your introduction should provide a brief explanation that supports this first statement. Divide the word limit by the three parts of your personal statement by allocating your introduction around 30%.
Once you have a good amount of information and several personal statement samples to reference you can then sit down and begin to put down your thoughts for your statement. Don't try to write your personal statement after only viewing one sample as this may inadvertently lead you to create a carbon copy of what you are looking at. By writing down your thoughts first you will be able to ensure that you are getting a good mix of ideas and inspirations from the various personal statement samples you like.