Tips on how to structure a SoP??

[chem.eng]

Hi guys!

 

I'm quite stuck here as I don't know where to start writing!

I am applying for PhD in top chemical engineering schools, and I want to include the following:

 

- my interest in biochemical industry and pharmaceutical research

- my research experience in biomaterial and nanofibers

- talk about myself as a person (me being a woman from a relatively developing country, all rounder personality, high general knowledge and global awareness)---> not sure what to write in personal qualities? 

- a low gpa semester (I was sick)

- why I think their program is best for me

 

But i just don't know the order and structure of such an essay and how much should I write on each aspect? 

What does the committee look for in an engineering PhD SoP?? 

 

Any help will be much appreciated