Preface help

Hi,

I’m new here. I’ve been writing a blog for 3 years, while working on my first non-fiction book of which most of the content is ready, I hope to finish it soon. That brought me to working on my Preface and I’d like to ask advice. I’m not sure how long it should be, my primary thought is I’d like it to hook the readers and want them to jump right in…

So please can you offer me critique on the following? Thanks.