Hi, I’m also applying for some competitive unis! For mine, I’ve gone with the 80/20% method, where you talk 80% about your subject and 20% about extra curriculars you do that aren’t subject related (musical instruments, sports, etc.)
It’s often easiest to leave the introduction until last, and I would definitely recommend doing that as honestly there’s nothing worse than sitting there with a blank page, just waiting for a break through statement to come. That’s just unproductive. It doesn’t matter if you write it in order at this stage, just write what you can.
Furthermore, what you write now isn’t going to be your final version. Write whatever comes to mind, then change it up and formalise it later on to make it more impressive. It seems much more manageable when you’ve got something on that piece of paper, whether it’s amazing or not.
My approach to it was first to write down every single thing I’ve done under different subheadings. First, I wrote “introduction”, and under that I got down all of the things I wanted to say just in bullet points, and any key sentences that I wanted to save for later when I wrote it up. Secondly, I wrote the subheading “in school”, in which I put down my subjects plus my EPQ. Then, I put “out of school”, which was my most important section. That contained all of the extra reading and studying I’d done around my subjects, an online course I’d done and an essay competition I entered. You can also write about work experience you’ve done if you’ve done any relating directly your subjects. Basically just put all of the academic stuff you’ve done that relates to your subject here. Finally, I put down a few extra bullet points about what I’ve done outside of school that is nothing to do with my subject, such as my grade 8 violin, my participation in orchestras, and the fact that I’m a Holocaust Educational Trust Ambassador.
I also wrote down in bullet points extra things I wanted to do before I apply to uni so I can have more stuff of my personal statement. However make sure you’re very clear about ticking off things you haven’t done and not ticking things you haven’t done. You should never lie in your personal statement, and if you get interviewed they may ask you about something you say you’ve read or studied.
I hope this helped you! I’m happy to help you further if you have any questions. Obviously I’m no expert, but I’m also applying to competitive unis and that’s just how I’ve done mine.