The purpose of a job interview is to help a potential employer to get to know what kind of an employee you would be, and to give you an opportunity to become more familiar with the employer. A general question like "tell me about yourself" may be intimidating, but it's also an opportunity to impress the interviewer.
Begin your answer to this introductory question with some basic information about yourself, including your background, where you grew up and a few of your interests relevant to the job you're appying for. Don't use up too much of your interview time with this information. Your job is to impress the interviewer with your skills, enthusiasm and experience, so basic information should only be a brief precursor. Tailor the information to the situation; if you happen to know that you and the interviewer share some interests or experiences, stress these common traits.
Tell the interviewer about your education. The more extensive your education has been and the more distinguished your performance, the more emphasis you should put on it, particularly if you have a lot of education and relatively little job experience. Don't just say where you attended college, share some impressive information about the university you attended, particularly as it relates to the field of work you are in. For example, if you are applying for a job at a communications company and your university has an outstanding, award-winning communications department, say so.
Your work experience is probably the most important aspect for you to convey clearly to your interviewer. While personal information helps you appear as a well-rounded and balanced person, the bottom line is that the interviewer is looking for an employee, and is trying to learn if you can do the job better than any other applicant. If you have had experience doing the job, this says a lot more than your education. Education implies that you would know what you were doing in the job, while work experience proves it.
Tooting Your Own Horn
A job interview is not the place to be shy. Don't be arrogant or overbearing, but make a point of conveying your achievements, your competencies and your gifts. If you are an outstanding writer, administrator, mechanic or teacher, leave that impression strongly in the interviewer's mind before you leave the interview. Practice with friends beforehand and get feedback about what tone will effectively convey confidence and enthusiasm without coming across as arrogance. All of the other applicants for the job will be selling themselves hard; if you don't do the same, you will appear unmotivated to the interviewer.