Tip 47 : Relevance is key
This is perhaps the single most important thing to remember when writing a personal statement, and it's about as close to a solid rule as we'll get.
Everything you include should be relevant.
If you've got incredible experiences or achievements that are highly impressive, but which you can't link back to the spec, leave them out. If you can link it back to the spec, then by all means do so, but if it's only a very tenuous link it's probably best to just leave it out.
I know this is difficult to do, but it is worth it - keep your eyes on the prize, and don't waste precious words on something that won't improve your chances of selection.
Tip 48 : You've read the question (RTQ)... Now answer it! (ATQ)
You've done great work so far; you owe it to yourself to make sure you take full advantage.
Make sure you address every element of the job/course spec, and include relevant examples and achievements for each. When I write a personal statement, I typically type out each of the requirements in the order I'm going to address them before I start. By doing this, I know I won't accidently miss anything, because I've got a reminder right there in my statement document.
You don't have to go this far if you don't want to - Like many writers I'm prone to mild obsessive-compulsive tendencies, so the idea of accidently missing something is truly terrible for me.
Whatever way you go about it, just make sure you don't miss anything.