I usually rewrite the first paragraph of all my books quite a lot, because it's important. Well, take that and multiply it by a hundred for a logline.
While Wattpad has a rule for loglines' structure, let's focus on the most important thing first.
Logline should sit here:
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It's what opens your book description. Its job is to make people want to check the book out. To do so, imo it should be fully (or nearly fully) visible. It should be crystal-clear why your book is totally great.
To me, the main things to shoot for are accuracy and max impact.
Accuracy is paramount. I used to run Champion in Love with a logline 'Spartacus, only gay'. It's hooking, but it's also misleading. The book is a queer love story, but while there is politics mixed in, gladiatorial combat is there, and the drama, there is no slave rebellion and the main character is nothing like Spartacus. To prevent people from going away disappointed, I changed this logline.
Impact roots in putting your strengths as a writer forward (just like summary), and your book's main selling point first. It can be a very brief statement. It can be a joke. It can be a description of the main character that makes them irresistible. Or it could be a natural conflict that blows people's minds (i.e. something like a tone-deaf, amusical person must judge the school's singing contest, their ex who knows about their problem entered it as well as the new love interest).
After you get that, you can work on the Wattpad's log-line structure which is basically: WHO must do WHAT, IN ORDER to achieve this, OR this undesirable thing happens. It's a solid structure. I want to emphasize what to me are the essentials: show your main character as much as possible, show the natural conflict that moves the story and make it clear that this conflict is rooted in the protagonist, so that your story can only happen to your protagonist.
The more you can intrigue people with the protagonist, their conflict and its rich possibilities in that one sentence, the better.
Sometimes, such intrigue can be created by a play on comp titles. Comp title is a book (trad, indie or Wattpad), a show or anything artistic that helps you describe your book via similarities and differences.
It can be a hybrid between two works: Tetrachromat has the time travel/college age protagonist similar to Umbrella Academy, and my protagonist also tries to solve an enduring cold case murder of a child-prince, like The Princes in the Tower.
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It can be just one reference with a cool twist, like, say, 'John Wick on a submarine'. When you do that, you want the twist to sound irresistibly cool, and even a bit whacky.
Comp titles also help you see how the authors of those books presented their summaries and loglines in search of an audience and if it worked for them.
Google or your library or Amazon are often your friend in your search for comps, throwing the key words in the search line. You can also browse lists of books recommended for specific themes or tropes, for example something like 'Revenge Novel with Fae'. Take a look at the stories that your search came up with, their summaries, sample pages if they are available to see if they work for you.
One thing I recommend is weighing the benefits of a famous match versus it not saying anything about your book. Over half the books on Wattpad can probably say they are Game of Thrones something or another. Game of Thrones defined at least a decade in grimdark and fantasy, so using it, just like using Twilight or Hunger Games or Harry Potter is on cross-purposes with finding a comp. It doesn't help you find your specific people. So, look for something that some people have heard of, but not absolutely everyone.
Even if you are not using comp titles for your logline, having them is a good practice and helps you with awareness of your subgenre.
The last thing I want to bring up is that don't be afraid to experiment with your loglines. Since your books all have different personalities, there is no one size fits them all loglines. Make them individual and captivating. Put them front and center. Ask other people to write it for you... see what works and have fun.
