I'm writing this post a little later than I originally anticipated (sorry!) but I hope it will still be of use to medicine applicants. The reason that it's a little late is because you probably should have started writing your personal statement by now if you want to apply to 2013 (even if it isn't yet a full draft). This is because the personal statement is a very important part of the application and you should dedicate a fair amount of time to writing it. Especially if you are yet to sit the UKCAT and are trying to balance UKCAT practice and PS writing.
Here are some tips for writing/improving your PS:
1. Quality over quantity. The is perhaps to most useful piece of information I was given when I applied last year. Even if you have a huge amount of work experience in a number of medical settings you will gain very little if you do not reflect upon your experiences adequately in your PS. It is very, very important to tell the admissions team what you learned for the experience and how it will help you at medical school/as a doctor. If you shadowed a doctor during work experience, try and remember how s/he behaved; how did they communicate with patients? Did they work effectively in a team? Was s/he understanding and empathetic? How did they cope when they were faced with a number of different tasks? The next step would then be to identify whether these traits are key parts of your own personality or how you have gained these important skills through your past experiences. You could then tie this in with your extra-curricular work. For example sports teams or orchestras can help you understand how to work in a team, working in a charity shop can improve your communication skills and confidence through dealing with the public and can also display long-term commitments. These are just two quick examples but, whatever your extra-curriculars happen to be, try to illustrate how they have been valuable to you. There is not point saying "I played in the schools football team for 5 years and won a number of trophies." if you aren't going to elaborate on it at all.
Back to the quality vs. quantity part, don't worry too much is you are somewhat lacking in work experience. The admissions department tend to understand that it is difficult to gain a lot of work experience. As long as you reflect well on the experience that you do have, your PS statement will be better than one that simply lists various placements without reflection.
2. Don't neglect extra-curriculars! With the tight UCAS limit, it can sometimes be tempting to miss out aspects of your experiences completely. Apart from the points I described above, extra-curriculars can also be a great way to show that you have a life outside academia. This is very important in medicine, in particular, as the job of a doctor is very demanding and often stressful. Therefore, it is important that you recognise this and say that playing an instrument (or whatever your activity is) helps you to relax and deal with stress.
3. Don't be cocky! The PS is the place where you are to show-off your skills and positive attributes. You do, after all, want the university to take you on. However, for some people it can be difficult to draw the line between self-confidence and arrogance. One way that helps to avoid this is to say things like "My teachers have often regarded me as..." rather than "I am...". Another thing could be to get a wide range of people to read over your PS as they may be able to point out parts that make you seem arrogant. This leads me to my next point...
4. Get as many people as possible to read over your PS. Guidance teachers and career's advisors, if available, are very useful as they should have a good knowledge of what medical schools look for. Sometimes class teachers, such as English, can be useful as well to check the layout and give an "outsider's" opinion. It can be a little embarrassing, but family members can also give you advice. They may even remind you to put somethings in that you forgot about.
5. Try not to be cheesy or use cliches. You should write about why you want to do medicine but try not to exaggerate. Phrases such as "a burning desire to help people" or "my fiery passion for human biology" will probably make admissions workers laugh at you.
6. This one goes without saying but BE HONEST! Does this really need an explanation? If you lie, the chances are that the experienced admissions team will see right through it. Also, if you are asked to elaborate (or even provide evidence!) during an interview, you will find yourself in a very sticky situation!
This has been a fairly quick post, so I may have missed a couple of things out. If you want further information, don't be scared to leave a comment below. I will try my best to answer!