Of course, I should add that I have yet submitted one to a publisher or agent as my book is not done yet, nor have i submitted my 40 word snippet, for the same reason, but:
This is a trick that I found very helpful - write the premise of your book as you would see it in the TV Guide if it were a movie, ex: An Island Sheriff battles a Great White shark hautning his resort town (Jaws). Even practice on your favorite books and movies. Once you can do it in a single line, it is much easier to work with a longer length. Espcially one up to 500 words.
Another suggestion for a long (500 word) synopsis. Write a sentence for your inciting incident, one for your beinning, one for the middle, one for the climax/resolution, and be sure to include plot points (major turning points). Then build on that. And write in present tense.
Sorry I didn't think of this before the deadline.
