I have a standard format:
Have you ever... XXX?
Asking a question of the reader right off the bat gets them thinking. It has to be a question that is fundamental to the core concept of your story, while being something that the Reader could imagine themselves being or living that experience. For example:
Have you ever wondered what it would be like to be Arachnid Lass?
Have you ever read the book Animal Plantation?
Have you ever imagined what it would be like to hit the lottery?
You ask this question to put the kernel of the main concept in the mind of the reader while asking them to imagine themselves as that they are the person experiencing the concept. If they like the idea, it will make them think about, "What is the answer to that question?" This is what is called your "Hook". No hook, no book.
After that, you have ONE PARAGRAPH. What I mean is, you can write as much as you want, but IF YOU DO NOT SELL THE READER ON THE VERY NEXT PARAGRAPH, YOUR BOOK IS DEAD. Your First Sentence is the Hook, but the next paragraph is your sales pitch. Minimum of 3 sentences, Maximum of 7, try to keep it to 4-5. DO NOT USED THE FOLLOWING WORDS, unless you are absolutely sure you need them:
Really, Feel, Think/Imagine, A Lot, Sort Of/Kind Of, Like, Used To - All of them are wishy-washy and you want your Synopsis to be STRONG.
Avoid the following:
BUT - But means, NEGATE EVERYTHING I JUST SAID BEFORE "BUT". You are wasting the reader's time when you use BUT in the synopsis.
AND - Chances are you are making a run on sentence. If you need "AND", make sure you only use it ONCE in any given sentence for your synopsis.
AS - This word means two things happen at once, and normally we don't do things at the exact same time. Therefore, this word is misused often. Know you are using it correctly if you use it.
JUST - This means, "ONLY" as in you ONLY DID THIS ONE THING. If you write, "John just stood there and screamed." John isn't JUST STANDING THERE. He is standing AND screaming. THE WORD IS MEANINGLESS AND WRONG. (Side note, this would be one of the few cases where you could use the word "AS" safely. For example, "John stood there AS he screamed.")
In fact, the advice about these words apply to your story as well. I'd avoid them as a rule. The exception being when people speak. It is okay for people to use these words when speaking and use them incorrectly. People speak poorly all the time. In fact, I often make a point when writing up a summary of a character, in my notes I will go, "Uses 'Just' often" or "Repeats himself." or something like that. Speaking can be messy, but your writing should be flawless as possible.
Then write your 1st paragraph sales pitch as best as you can. Avoid being too fancy. Simple, direct, to the point. Hit the reader as hard as you can and get them thinking. Then maybe make some clarification paragraphs afterward if you feel like it. Just don't contradict your opening sentence or the first paragraph.
You can use something more aggressive than a question, if that's your style. For example:
Imagine if you will a world where your dick detaches itself at night to go flying through the astral plane to go hang out on with other penises at nightclubs.
Think about what it would be like to be made of living fire.
Contemplate a world where The Eldritch God isn't a fuckin' pompous pretentious know-it-all.
I prefer a question to open, as it is less aggressive, but depending on the style of your book, you might want to COMMAND the reader to think about a given concept. I'd avoid it if you are new, but these are just guidelines. If a thing works, it works.
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Addendum: KNOW WHAT YOUR WORDS MEAN TO YOU.
What I mean is, all words have a definition, but maybe you don't FEEL a word means what everyone else thinks it means. This is how language changes over time. Slang changes meaning.
The Bee's Knees
That's Awesome
That Slaps
Tubular
They all mean the same thing, but are also dated in time as to exactly what they mean both to you, the characters and your reader.
Whatever you type, BE CONSISTANT.
What I mean is, if you use Tubular, make sure you know what it means to you and use it the same way every time. if YOU start changing how you think/feel a word means, even if it's a little bit, your reader will figure it out and it will ruin the reading experience. If you use a word WRONG, keep using it the wrong way, every time, in the exact same way. Your reader might be confused at first, but it will get worse if you try to correct it later.
