Actually, I think starting your answer with: "I'm (name), (age) years old and I have a number of interests including (subject relevant to job, e.g. economics) " is direct, and serves as an introduction.
Remember that they'll have probably absorbed only 10% of your application form/ CV as they've had to trawl through so many, and they'll have done so on the train to work. They may have at one stage calculated your age from your date of birth but won't recall.
Also, 'tell me about yourself' is about what kind of person you are - they're not just interested in your skills, primarily do you come across as amiable, open, articulate, honest in the presentation of yourself?
You can develop on your skills/ work experience later in the interview - if I were an interviewer, I'd like to know a bit about you first, your interests and whether you seem to have a personality I can get on with.