Your personal statement is one of the hardest things you may have to write, and yet you know the subject matter by heart---it's all about you. With that in mind, treat the statement for what it is: You are showing off to the reader. A key to a good personal statement is remembering to make the statement about you. Do not go off on tangents, and above all, do not highlight any negative or suspect information about yourself. If you have trouble writing about yourself, imagine you are writing this statement about one of your best friends. Do not lose focus about the topic.
The goal of the personal statement is easy: Earn an acceptance into some program or club. Remember, however, that every applicant writing a personal statement knows this and has this in mind. You need to be different. Your personal statement needs to make an impression. A good way to do that is to write your statement around a theme. Whatever theme you choose, make sure it has some relevance to your application. If you are applying for law school, highlight your analytical traits. Explain some situations in which you applied these skills. Tell a story, and show the reader the person behind the words. A theme will help you accomplish that.
No one enjoys being lectured. Likewise, people tend to lose focus when we are not qualifying our language. Instead of writing "I am motivated. I study hard. I strive to succeed," demonstrate those qualities with concrete and meaningful examples. How are you motivated? Tell the reader about a time in your life when being motivated helped you accomplish a hard task. Illustrate every quality you have with an example.
Above all, make sure that your personal statement is error-free. If you do not have great writing skills, think seriously about taking the statement to a professional editor before submitting it. Readers will find grammatical errors immediately, and this type of oversight can be devastating to your statement. It shows the reader that you did not take the time to make this statement perfect, which suggests you might be lazy or careless. Proofread your statement carefully, and correct any spelling errors and grammatical mistakes. Also, use clear language when writing your statement. Avoid long sentences and convoluted sentence structure. Make reading the statement easy on your reader.