Well, first of all what kind of summary do I mean? A real summary is long and comprises of your entire story; plot twists, character decisions, everything, and you'd send this summary to a publisher if you were submitting your story.
OR there's a Wattpad summary, which is actually a 'blurb'. This is what you find on the backs of books. For a Wattpad summary you need to:
-briefly introduce your main character
-tell us what the main conflict is (what does your MC have to overcome, is there a villain?)
-show us why this story will be interesting
So let's have an example. If you had a story about an ipoverished kid who joins a street gang to pay for his sick mother's medical treatment, and then his convict father returns to mess things up, you might write:
"With a dying mother and no way out, dealing some dope around the estate seems to be Robbi's only future. (that's the MC introduced) But when his jail-bound father returns (conflict) to the block for payback,(reader thinks 'payback for what?' and wants to read on) Robbi makes the mistake he's been planning for years (a strange concpt, reader is intrigued)."
You notice there are no rhetorical questions. No ambiguous 'and he must do something'. No cliches. No unnecessary information like 'growing up, Robbi had a hard life, but doesn't everyone?' It's really easy to elaborate too far with flowery wording, but all you're trying to do is explain why your story is worth someone's time.
Make it straight to the point, make it interesting, make it relevant, and you'll have plenty of people clicking 'READ NOW'!