Throughout the application process, I've learnt a few things that I would have loved to have known at the beginning.

i) Have a team of people to support you in your essay writing. Readers and editors. Preferably, get a current student (though they're always busy), an admit (only if you're applying for round 2 onwards), another applicant (somebody you feel that you can trust not to rip off your content - which is harder than it seems especially if you've got different goals) and a phd student as a proof reader.

ii) Don't be afraid to re-write your essay from scratch. Or re-structure something that you've just spend 3 weeks perfecting. Sometimes it's worth the pain and trouble. I think the saying is "Don't be afraid to kill your babie." Because if you don't, you might never improve your essay.

iii) You can get sick of writing essays. After looking at an essay for the 20th time, you're bound to feel brain dead when it comes to editing it. Take a break for a day or two. Do something else different.

iv) Each paragraph should have a situation - action - result, and a focus. Crop off anything that dilutes that focus.

v) Your goals don't have to be unique. But you must be able to relate to them.

I'll add more stuff when I remember and think of it.