How do I start writing a personal statement

First, what is a personal statement? Personal statements are essays about yourself, where you try to convince the reader (the admissions team) that you are without a shadow of a doubt the right person for that course for their university.

In the UK you'll be writing these to several universities with sometimes different courses; the universities know this. However there should be internal consistency that is applicable to all the courses you are applying to.

To write a personal statement, you need experience. Schools usually bring personal statements up in the final year of high school, which I always say is too late, since you cannot get all the experience you need in less than a year's time. By experience I mean anything that will make you standout as a person - that can be playing an instrument, teaching younger students, debate team, sports teams, charity work, paid work. Where to get experience and what is relevant experience is a question that demands a seperate answer.

Let's say you already have your experience for the sake of this question. You now need to organize it based on topics. I would go for the following: 1) academic achievement, 2) extracurricular achievement, 3) hobbies, 4) personal interests. These are all in order of importance. If you feel that any one of these categories is lacking, then you need to get experience in that category ASAP. 

Example 1: 

"You are top of your class in most subjects that are relevant to your course, however you have very little extracurricular achievements. You are a one-trick pony and a bit boring. A bookworm. You want some spice in your life. Therefore you need to focus on personal interests and extracurriculars. If you are good academically, teaching younger students or your fellow classmates can work. Organize lectures or revision for the younger years e.g. if you are A-level/IB then teach GCSE level students."

Example 2:

"You are athletic, captain of a sports team. Your grades are all right, slightly above average, and you are involved in a lot of charity work. In this case, boosting your grades to be as high as possible would be the priority. You have every other category; you just need to focus on getting good predicted grades for your course."

In order to construct your perfect essay about yourself you need to organize your experience and see what else you need. I recommend being conscious about this early on in high school. Otherwise you will be stressed out.