Good morning! My name is David Jones and I'm here to talk about covering letters.
The most important thing about applying for a job is that the letter you send should be clear, positive and short. You obviously have to include basic information like your name and address, and a number where they can contact you, but I'd leave out other personal information. Don't state your age, for example, you can put in your date of birth in your CV if you wish, but I think it's preferable to let the employer work that out from the dates of your education. And there's certainly no need to include anything about your family. Don't mention children or parents! I think work experience is more important than education, unless of course you're applying straight from school.
Remember that you are not creating a flyer or a poster, so avoid using colours. Black on white reproduces easily. Use a plain white paper.
Those are the essentials. Then there are a few less important details. Mention spare-time interests if you can make them memorable, not just things like reading and stamp collecting. And put in your achievements, if you've done something you're particularly proud of. And if it's a big company, don't forget to say exactly what job you're applying for.
Thanks for your attention.